I was running the 0.9 version previously.  I upgraded to the 0.10-dev version before rerunning the conversion:

peterc@popeye:~/bin/svn2bzr$ sudo ./svn2bzr.py ~/tmp/svn-repos-dump-full_20090401-0130 /var/bzr

I get the same error:

Committed revision 169
Committed revision 170
Committed revision 171
Nothing changed in revision 172
...but committing revision properties (revno, message, committer, and timestamp) anyways
Committed revision 172
Changing dir: /var/bzr/trunk/myusers
warning: Code for changing dir properties is unimplemented.
	dir: /var/bzr/trunk/myusers
	property: {'svn:ignore': 'UserFormControllerTest_output.txt\nZacksTool.sptl'} remains unchanged
Changing dir: /var/bzr/trunk/myusers/web/WEB-INF/classes
warning: Code for changing dir properties is unimplemented.
	dir: /var/bzr/trunk/myusers/web/WEB-INF/classes
	property: {'svn:ignore': 'images\nMETA-INF\norg'} remains unchanged
Traceback (most recent call last):
  File "./svn2bzr.py", line 1637, in <module>
    main()
  File "./svn2bzr.py", line 1630, in main
    log=log)
  File "./svn2bzr.py", line 1531, in svn2bzr
    creator.run()
  File "./svn2bzr.py", line 682, in run
    self.commit_revision(revno, revision)
  File "./svn2bzr.py", line 664, in commit_revision
    timestamp=timestamp, timezone=offset)
  File "./svn2bzr.py", line 547, in commit
    timestamp, timezone)
  File "./svn2bzr.py", line 584, in commit_brt
    verbose=False)
  File "<string>", line 4, in commit_write_locked
  File "/usr/lib/python2.5/site-packages/bzrlib/workingtree_4.py", line 225, in commit
    result = WorkingTree3.commit(self, message, revprops, *args, **kwargs)
  File "<string>", line 4, in commit_write_locked
  File "/usr/lib/python2.5/site-packages/bzrlib/mutabletree.py", line 228, in commit
    *args, **kwargs)
  File "/usr/lib/python2.5/site-packages/bzrlib/commit.py", line 384, in commit
    self.rev_id = self.builder.commit(self.message)
  File "/usr/lib/python2.5/site-packages/bzrlib/repository.py", line 149, in commit
    self._validate_unicode_text(message, 'commit message')
  File "/usr/lib/python2.5/site-packages/bzrlib/repository.py", line 132, in _validate_unicode_text
    raise ValueError('Invalid value for %s: %r' % (context, text))
ValueError: Invalid value for commit message: u'Copied Chapter 5 (SiteMesh) complete over ZacksTool. Defines new baseline. \r\nRenamed org.appfuse to org.alembix.\n'

Here are two portions of the SVN dump file around the above line that is causing the error:

  <component name="VCS.FileViewConfiguration">
    <option name="SELECTED_STATUSES" value="DEFAULT" />
    <option name="SELECTED_COLUMNS" value="DEFAULT" />
    <option name="SHOW_FILTERS" value="true" />
    <option name="CUSTOMIZE_VIEW" value="true" />
    <option name="SHOW_FILE_HISTORY_AS_TREE" value="true" />
  </component>
  <component name="VcsManagerConfiguration">
    <option name="CHECK_CODE_SMELLS_BEFORE_PROJECT_COMMIT" value="true" />
    <option name="PUT_FOCUS_INTO_COMMENT" value="false" />
    <option name="FORCE_NON_EMPTY_COMMENT" value="false" />
    <option name="LAST_COMMIT_MESSAGE" value="Copied Chapter 5 (SiteMesh) complete over ZacksTool. Defines new baseline. &#10;Renamed o
    <option name="SAVE_LAST_COMMIT_MESSAGE" value="true" />
    <option name="CHECKIN_DIALOG_SPLITTER_PROPORTION" value="0.8" />
    <option name="OPTIMIZE_IMPORTS_BEFORE_PROJECT_COMMIT" value="false" />
    <option name="OPTIMIZE_IMPORTS_BEFORE_FILE_COMMIT" value="false" />
    <option name="REFORMAT_BEFORE_PROJECT_COMMIT" value="false" />
    <option name="REFORMAT_BEFORE_FILE_COMMIT" value="false" />
    <option name="FILE_HISTORY_DIALOG_COMMENTS_SPLITTER_PROPORTION" value="0.8" />
    <option name="FILE_HISTORY_DIALOG_SPLITTER_PROPORTION" value="0.5" />
    <option name="ERROR_OCCURED" value="true" />
    <option name="ACTIVE_VCS_NAME" value="CVS" />
    <option name="UPDATE_GROUP_BY_PACKAGES" value="false" />
    <option name="SHOW_FILE_HISTORY_AS_TREE" value="false" />
    <option name="FILE_HISTORY_SPLITTER_PROPORTION" value="0.6" />
    <MESSAGE value="Copied Chapter 5 (SiteMesh) complete over ZacksTool. Defines new baseline. &#10;Renamed org.appfuse to org.alembix.
  </component>
  <component name="VssConfiguration">
    <option name="CLIENT_PATH" value="" />
    <option name="SRCSAFEINI_PATH" value="" />
    <option name="USER_NAME" value="" />
    <option name="PWD" value="" />
    <option name="VSS_IS_INITIALIZED" value="true" />
    <CheckoutOptions>
      <option name="COMMENT" value="" />
      <option name="DO_NOT_GET_LATEST_VERSION" value="false" />
      <option name="REPLACE_WRITABLE" value="false" />
      <option name="RECURSIVE" value="false" />
    </CheckoutOptions>
    <CheckinOptions>
      <option name="COMMENT" value="" />
      <option name="KEEP_CHECKED_OUT" value="false" />
      <option name="RECURSIVE" value="false" />
    </CheckinOptions>
    <AddOptions>
      <option name="COMMENT" value="" />
      <option name="STORE_ONLY_LATEST_VERSION" value="false" />
      <option name="CHECK_OUT_IMMEDIATELY" value="false" />
      <option name="FILE_TYPE" value="0" />
    </AddOptions>
    <UndocheckoutOptions>
      <option name="MAKE_WRITABLE" value="false" />
      <option name="REPLACE_LOCAL_COPY" value="0" />
      <option name="RECURSIVE" value="false" />
    </UndocheckoutOptions>
    <GetOptions>
      <option name="REPLACE_WRITABLE" value="0" />
      <option name="MAKE_WRITABLE" value="false" />
      <option name="RECURSIVE" value="false" />
    </GetOptions>
  </component>



------------------------------------------------------------------------
r174 | peterc | 2006-08-02 22:41:59 -0700 (Wed, 02 Aug 2006) | 2 lines
Changed paths:
   M /trunk/myusers/ZacksTool.iml
   M /trunk/myusers/ZacksTool.ipr
   M /trunk/myusers/ZacksTool.iws
   M /trunk/myusers/web/WEB-INF/applicationContext.xml
   M /trunk/myusers/web/WEB-INF/classes/log4j.xml
   M /trunk/myusers/web/WEB-INF/classes/messages.properties
   M /trunk/myusers/web/WEB-INF/sitemesh.xml
   M /trunk/myusers/web/WEB-INF/validator-rules.xml
   M /trunk/myusers/web/taglibs.jsp

Copied Ch5 baseline over to ZacksTool.

------------------------------------------------------------------------
r173 | peterc | 2006-08-02 22:37:49 -0700 (Wed, 02 Aug 2006) | 3 lines
Changed paths:
   M /trunk/myusers
   M /trunk/myusers/.classpath
   A /trunk/myusers/.cvsignore
   M /trunk/myusers/.project
   A /trunk/myusers/ZacksTool.iml
   A /trunk/myusers/ZacksTool.ipr
   A /trunk/myusers/ZacksTool.iws
   M /trunk/myusers/build.xml
   D /trunk/myusers/myusers.iml
   D /trunk/myusers/myusers.ipr
   D /trunk/myusers/myusers.iws
   A /trunk/myusers/src/org/alembix
   A /trunk/myusers/src/org/alembix/dao
   A /trunk/myusers/src/org/alembix/dao/DAO.java
   A /trunk/myusers/src/org/alembix/dao/UserDAO.java
   A /trunk/myusers/src/org/alembix/dao/hibernate
   A /trunk/myusers/src/org/alembix/dao/hibernate/UserDAOHibernate.java
   A /trunk/myusers/src/org/alembix/model
   A /trunk/myusers/src/org/alembix/model/BaseObject.java
   A /trunk/myusers/src/org/alembix/model/User.hbm.xml
   A /trunk/myusers/src/org/alembix/model/User.java
   A /trunk/myusers/src/org/alembix/service
   A /trunk/myusers/src/org/alembix/service/UserManager.java
   A /trunk/myusers/src/org/alembix/service/impl
   A /trunk/myusers/src/org/alembix/service/impl/UserManagerImpl.java
   A /trunk/myusers/src/org/alembix/web
   A /trunk/myusers/src/org/alembix/web/UserController.java
   A /trunk/myusers/src/org/alembix/web/UserFormController.java
   D /trunk/myusers/src/org/appfuse
   A /trunk/myusers/test/org/alembix
   A /trunk/myusers/test/org/alembix/dao
   A /trunk/myusers/test/org/alembix/dao/BaseDAOTestCase.java
   A /trunk/myusers/test/org/alembix/dao/UserDAOTest.java
   A /trunk/myusers/test/org/alembix/service
   A /trunk/myusers/test/org/alembix/service/UserManagerTest.java
   A /trunk/myusers/test/org/alembix/web
   A /trunk/myusers/test/org/alembix/web/BaseControllerTestCase.java
   A /trunk/myusers/test/org/alembix/web/UserControllerTest.java
   A /trunk/myusers/test/org/alembix/web/UserFormControllerTest.java
   D /trunk/myusers/test/org/appfuse
   M /trunk/myusers/web/WEB-INF/action-servlet.xml
   M /trunk/myusers/web/WEB-INF/applicationContext.xml
   M /trunk/myusers/web/WEB-INF/classes
   A /trunk/myusers/web/WEB-INF/classes/.cvsignore
   M /trunk/myusers/web/WEB-INF/classes/log4j.xml
   A /trunk/myusers/web/WEB-INF/lib/activation.jar
   A /trunk/myusers/web/WEB-INF/lib/mail.jar
   A /trunk/myusers/web/WEB-INF/lib/struts.jar
   M /trunk/myusers/web/WEB-INF/sitemesh.xml
   M /trunk/myusers/web/taglibs.jsp

Copied Chapter 5 (SiteMesh) complete over ZacksTool. Defines new baseline. 
Renamed org.appfuse to org.alembix.

------------------------------------------------------------------------
r172 | peterc | 2006-08-02 20:23:19 -0700 (Wed, 02 Aug 2006) | 2 lines

baselining ZacksTool from working myusers, with appfuse db

------------------------------------------------------------------------

Let me know if you need any more info.

When I use the --scheme=trunk option, I get a different error.  

Nothing changed in revision 1
...but committing revision properties (revno, message, committer, and timestamp) anyways
Traceback (most recent call last):
  File "./svn2bzr.py", line 1637, in <module>
    main()
  File "./svn2bzr.py", line 1630, in main
    log=log)
  File "./svn2bzr.py", line 1531, in svn2bzr
    creator.run()
  File "./svn2bzr.py", line 682, in run
    self.commit_revision(revno, revision)
  File "./svn2bzr.py", line 664, in commit_revision
    timestamp=timestamp, timezone=offset)
  File "./svn2bzr.py", line 555, in commit
    timestamp, timezone)
  File "./svn2bzr.py", line 570, in commit_brt
    rel_branch_path = brt.tree.relpath(self._root)
  File "/usr/lib/python2.5/site-packages/bzrlib/workingtree.py", line 433, in relpath
    return osutils.relpath(self.basedir, path)
  File "/usr/lib/python2.5/site-packages/bzrlib/osutils.py", line 966, in relpath
    raise errors.PathNotChild(rp, base)
bzrlib.errors.PathNotChild: Path "/var/bzr" is not a child of path "/var/bzr/trunk"

Should I create a bug for that too?