Bad error message when EDITOR is not set.

[xxx]

example:
% unset EDITOR
% bzr commit
bzr: ERROR: [Errno 2] No such file or directory
  command: '/usr/bin/bzr' 'commit'
      pwd: u'xxx.py'
    error: exceptions.OSError
  at /usr/lib/python2.4/subprocess.py line 975, in _execute_child()
  see ~/.bzr.log for debug information
%

Traceback (most recent call last):
  File "/usr/lib/python2.4/site-packages/bzrlib/commands.py", line 522, in run_bzr_catch_errors
    return run_bzr(argv)
  File "/usr/lib/python2.4/site-packages/bzrlib/commands.py", line 497, in run_bzr
    ret = cmd_obj.run_argv(argv)
  File "/usr/lib/python2.4/site-packages/bzrlib/commands.py", line 215, in run_argv
    return self.run(**all_cmd_args)
  File "/usr/lib/python2.4/site-packages/bzrlib/builtins.py", line 1104, in run
    message = edit_commit_message(catcher.getvalue())
  File "/usr/lib/python2.4/site-packages/bzrlib/msgeditor.py", line 92, in edit_commit_message
    if not _run_editor(msgfilename):
  File "/usr/lib/python2.4/site-packages/bzrlib/msgeditor.py", line 54, in _run_editor
    x = call(edargs + [filename])
  File "/usr/lib/python2.4/subprocess.py", line 412, in call
    return Popen(*args, **kwargs).wait()
  File "/usr/lib/python2.4/subprocess.py", line 542, in __init__
    errread, errwrite)
  File "/usr/lib/python2.4/subprocess.py", line 975, in _execute_child
    raise child_exception
OSError: [Errno 2] No such file or directory

[John A Meinel (jameinel)]

In 0.7 if EDITOR and BZR_EDITOR are not set, bzr tries to use a reasonable editor based on platform.

However, if EDITOR is set to something non-existant, we fail to trap the exception.
$ EDITOR=bogus bzr commit
bzr: ERROR: exceptions.OSError: [Errno 2] No such file or directory
  at /usr/lib/python2.4/subprocess.py line 975
  in _execute_child

We probably just want a try/except around the subprocess.call() function at line 54 in msgeditor.py

Something like this:
=== modified file 'bzrlib/msgeditor.py'
--- bzrlib/msgeditor.py
+++ bzrlib/msgeditor.py
@@ -20,6 +20,7 @@
 """Commit message editor support."""

 import os
+import errno
 from subprocess import call

 import bzrlib.config as config
@@ -51,7 +52,13 @@
     """Try to execute an editor to edit the commit message."""
     for e in _get_editor():
         edargs = e.split(' ')
- x = call(edargs + [filename])
+ try:
+ x = call(edargs + [filename])
+ except OSError, e:
+ # ENOENT means no such editor
+ if e.errno == errno.ENOENT:
+ continue
+ raise
         if x == 0:
             return True
         elif x == 127:

Present on my jam-pending branch (revno 1509)