Enforces using cwd in all svn calls.

trychange.py

 #!/usr/bin/env python
 # Copyright (c) 2011 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """Client-side script to send a try job to the try server. It communicates to
 the try server by either writting to a svn repository or by directly connecting
 to the server by HTTP.
 """
 
@@ skipping 226 matching lines @@
       return data
 
     # Try to search on the subversion repository for the file.
     if not gcl:
       return None
     data = gcl.GetCachedFile(filename)
     logging.debug('%s:\n%s' % (filename, data))
     return data
 
   def CaptureStatus(self):
-    previous_cwd = os.getcwd()
-    os.chdir(self.checkout_root)
-    result = scm.SVN.CaptureStatus(self.checkout_root)
-    os.chdir(previous_cwd)
-    return result
+    return scm.SVN.CaptureStatus(None, self.checkout_root)
 
   def GenerateDiff(self):
     """Returns a string containing the diff for the given file list.
 
     The files in the list should either be absolute paths or relative to the
     given root.
     """
     return scm.SVN.GenerateDiff(self.files, self.checkout_root, full_move=True,
                                 revision=self.diff_against)
 
@@ skipping 199 matching lines @@
     return GIT(options, path, file_list)
   except OSError, e:
     if e.errno != errno.ENOENT:
       raise
   except subprocess2.CalledProcessError, e:
     if e.returncode != errno.ENOENT and e.returncode != 128:
       # ENOENT == 2 = they don't have git installed.
       # 128 = git error code when not in a repo.
       logging.warning('Unexpected error code: %s' % e.returncode)
       raise
-  raise NoTryServerAccess("Could not guess version control system. "
-                          "Are you in a working copy directory?")
+  raise NoTryServerAccess(
+      ( 'Could not guess version control system for %s.\n'
+        'Are you in a working copy directory?') % path)
 
 
 def GetMungedDiff(path_diff, diff):
   # Munge paths to match svn.
   changed_files = []
   for i in range(len(diff)):
     if diff[i].startswith('--- ') or diff[i].startswith('+++ '):
       new_file = posixpath.join(path_diff, diff[i][4:]).replace('\\', '/')
       if diff[i].startswith('--- '):
         file_path = new_file.split('\t')[0].strip()
@@ skipping 331 matching lines @@
     return 1
   except (gclient_utils.Error, subprocess2.CalledProcessError), e:
     print >> sys.stderr, e
     return 1
   return 0
 
 
 if __name__ == "__main__":
   fix_encoding.fix_encoding()
   sys.exit(TryChange(None, None, False))