gclient: Add better error reporting and handling when there is a rebase conflict

gclient_scm.py

 # Copyright (c) 2009 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.
 
 """Gclient-specific SCM-specific operations."""
 
 import logging
 import os
 import re
 import subprocess
@@ skipping 122 matching lines @@
                 cwd=self._root_dir, redirect_stdout=False)
       if revision:
         self._Run(['reset', '--hard', revision], redirect_stdout=False)
       files = self._Run(['ls-files']).split()
       file_list.extend([os.path.join(self.checkout_path, f) for f in files])
       return
 
     new_base = 'origin'
     if revision:
       new_base = revision
-    cur_branch = self._Run(['symbolic-ref', 'HEAD']).split('/')[-1]
+    cur_branch = self._GetCurrentBranch()
+
+    # Check if we are in a rebase conflict
+    if cur_branch is None:
+      raise gclient_utils.Error('\n____ %s%s\n'
+                                '\tAlready in a conflict, i.e. (no branch).\n'
+                                '\tFix the conflict and run gclient again.\n'
+                                '\tOr to abort run:\n\t\tgit-rebase --abort\n'
+                                '\tSee man git-rebase for details.\n'
+                                 % (self.relpath, rev_str))
+
     merge_base = self._Run(['merge-base', 'HEAD', new_base])
     self._Run(['remote', 'update'], redirect_stdout=False)
     files = self._Run(['diff', new_base, '--name-only']).split()
     file_list.extend([os.path.join(self.checkout_path, f) for f in files])
     self._Run(['rebase', '-v', '--onto', new_base, merge_base, cur_branch],
-                redirect_stdout=False)
+                redirect_stdout=False, checkrc=False)
+
+    # If the rebase generated a conflict, abort and ask user to fix
+    if self._GetCurrentBranch() is None:
+      raise gclient_utils.Error('\n____ %s%s\n'
+                                '\nConflict while rebasing this branch.\n'
+                                'Fix the conflict and run gclient again.\n'
+                                'See man git-rebase for details.\n'
+                                % (self.relpath, rev_str))
+
     print "Checked out revision %s." % self.revinfo(options, (), None)
 
   def revert(self, options, args, file_list):
     """Reverts local modifications.
 
     All reverted files will be appended to file_list.
     """
     __pychecker__ = 'unusednames=args'
     path = os.path.join(self._root_dir, self.relpath)
     if not os.path.isdir(path):
@@ skipping 37 matching lines @@
     version_list = map(only_int, version.split('.'))
     min_version_list = map(int, min_version.split('.'))
     for min_ver in min_version_list:
       ver = version_list.pop(0)
       if min_ver > ver:
         raise gclient_utils.Error('git version %s < minimum required %s' %
                                   (version, min_version))
       elif min_ver < ver:
         return
 
+  def _GetCurrentBranch(self):
+    # Returns name of current branch
+    # Returns None if inside a (no branch)
+    tokens = self._Run(['branch']).split()
+    branch = tokens[tokens.index('*') + 1]
+    if branch == '(no':
+      return None
+    return branch
+
   def _Run(self, args, cwd=None, checkrc=True, redirect_stdout=True):
     # TODO(maruel): Merge with Capture?
     if cwd is None:
         cwd = self.checkout_path
     stdout=None
     if redirect_stdout:
       stdout=subprocess.PIPE
     if cwd == None:
       cwd = self.checkout_path
     cmd = [self.COMMAND]
@@ skipping 262 matching lines @@
           self.ReplaceAndPrint(line)
         else:
           if (line.startswith(self.original_prefix) or
               line.startswith(self.working_prefix)):
             self.ReplaceAndPrint(line)
           else:
             print line
 
     filterer = DiffFilterer(self.relpath)
     self.RunAndFilterOutput(command, path, False, False, filterer.Filter)