Fix git-map-branches crashing on HEAD, and other minor quality-of-life

git_map_branches.py

 #!/usr/bin/env python
 # Copyright 2014 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.
 
 """Provides a short mapping of all the branches in your local repo, organized
 by their upstream ('tracking branch') layout.
 
 Example:
 origin/master
@@ skipping 14 matching lines @@
 """
 
 import argparse
 import collections
 import sys
 
 from third_party import colorama
 from third_party.colorama import Fore, Style
 
 from git_common import current_branch, upstream, tags, get_branches_info
-from git_common import get_git_version, MIN_UPSTREAM_TRACK_GIT_VERSION
-
-import git_cl
+from git_common import get_git_version, MIN_UPSTREAM_TRACK_GIT_VERSION, hash_one
 
 DEFAULT_SEPARATOR = ' ' * 4
 
 
 class OutputManager(object):
   """Manages a number of OutputLines and formats them into aligned columns."""
 
   def __init__(self):
     self.lines = []
     self.nocolor = False
@@ skipping 86 matching lines @@
         if branch_upstream:
           parent = branch_upstream
         else:
           self.__gone_branches.add(parent)
         # A parent that isn't in the branches info is a root.
         roots.add(parent)
 
       self.__parent_map[parent].append(branch)
 
     self.__current_branch = current_branch()
-    self.__current_hash = self.__branches_info[self.__current_branch].hash
+    self.__current_hash = hash_one('HEAD', short=True)
     self.__tag_set = tags()
 
-    for root in sorted(roots):
-      self.__append_branch(root)
+    if roots:
+      for root in sorted(roots):
+        self.__append_branch(root)
+    else:
+      no_branches = OutputLine()
+      no_branches.append('No User Branches')
+      self.output.append(no_branches)
 
   def __is_invalid_parent(self, parent):
     return not parent or parent in self.__gone_branches
 
   def __color_for_branch(self, branch, branch_hash):
     if branch.startswith('origin'):
       color = Fore.RED
     elif self.__is_invalid_parent(branch) or branch in self.__tag_set:
       color = Fore.MAGENTA
-    elif branch_hash == self.__current_hash:
+    elif self.__current_hash.startswith(branch_hash):
       color = Fore.CYAN
     else:
       color = Fore.GREEN
 
-    if branch_hash == self.__current_hash:
+    if self.__current_hash.startswith(branch_hash):
       color += Style.BRIGHT
     else:
       color += Style.NORMAL
 
     return color
 
   def __append_branch(self, branch, depth=0):
     """Recurses through the tree structure and appends an OutputLine to the
     OutputManager for each branch."""
     branch_info = self.__branches_info[branch]
-    branch_hash = branch_info.hash if branch_info else None
+    if branch_info:
+      branch_hash = branch_info.hash
+    else:
+      branch_hash = hash_one(branch, short=True)
 
     line = OutputLine()
 
     # The branch name with appropriate indentation.
     suffix = ''
     if branch == self.__current_branch or (
         self.__current_branch == 'HEAD' and branch == self.__current_hash):
       suffix = ' *'
     branch_string = branch
     if branch in self.__gone_branches:
@@ skipping 33 matching lines @@
           center_separator = '|'
 
       line.append(front_separator, separator=' ')
       line.append(ahead_string, separator=' ', color=Fore.MAGENTA)
       line.append(center_separator, separator=' ')
       line.append(behind_string, separator=' ', color=Fore.MAGENTA)
       line.append(back_separator)
 
     # The Rietveld issue associated with the branch.
     if self.verbosity >= 2:
+      import git_cl  # avoid heavy import cost unless we need it
       none_text = '' if self.__is_invalid_parent(branch) else 'None'
       url = git_cl.Changelist(branchref=branch).GetIssueURL()
       line.append(url or none_text, color=Fore.BLUE if url else Fore.WHITE)
 
     self.output.append(line)
 
     for child in sorted(self.__parent_map.pop(branch, ())):
       self.__append_branch(child, depth=depth + 1)
 
 
@@ skipping 16 matching lines @@
   opts = parser.parse_args(argv[1:])
 
   mapper = BranchMapper()
   mapper.verbosity = opts.v
   mapper.output.nocolor = opts.nocolor
   mapper.start()
   print mapper.output.as_formatted_string()
 
 if __name__ == '__main__':
   sys.exit(main(sys.argv))