`setup.py --help-commands` requires SVN_DEV, but shouldn't be

[Alexander Belchenko]

C:\work\Bazaar\zzz\subvertpy>setup.py --help-commands
Traceback (most recent call last):
  File "C:\work\Bazaar\zzz\subvertpy\setup.py", line 254, in <module>
    (svn_includedirs, svn_libdirs, svn_link_flags, extra_libs) = svn_build_data()
  File "C:\work\Bazaar\zzz\subvertpy\setup.py", line 197, in svn_build_data
    "Please set SVN_DEV to the location of the svn development "
Exception: Please set SVN_DEV to the location of the svn development packages.
These can be downloaded from:
http://subversion.tigris.org/servlets/ProjectDocumentList?folderID=91