Issue 2311 - Track remote Git branches when required

ensure_dependencies.py

Index: ensure_dependencies.py
diff --git a/ensure_dependencies.py b/ensure_dependencies.py
index 9f2bcc7b7d8feec57b10e4c6d8b62989171ac8ff..1de24a2c1919e9b368748586c5bf1c1ae67c410b 100755
--- a/ensure_dependencies.py
+++ b/ensure_dependencies.py
@@ -97,7 +97,20 @@ class Git():
     return subprocess.check_output(command, cwd=repo).strip()
 
   def pull(self, repo):
+    # Fetch tracked branches, new tags and the list of available remote branches
     subprocess.check_call(["git", "fetch", "--quiet", "--all", "--tags"], cwd=repo)
+    # Next we need to ensure all remote branches are tracked
+    newly_tracked = False
+    remotes = subprocess.check_output(["git", "branch", "--remotes"], cwd=repo)
+    for match in re.finditer(r"(?:^|\s)(origin/(\S+))", remotes):

[Sebastian Noack, 2015/05/06 14:45:12]

I just realized that this regexp will find the branch checkout in the remote
repository twice, e.g:

  origin/HEAD -> origin/master
  origin/master

Not a big deal, but you can simply avoid that without adding any complexity:

  re.finditer(r"^\s*(origin/(\S+))", remotes, re.M)

[kzar, 2015/05/06 15:11:13]

Oh yea, also I realised if we check for the end of the line too we actually can
skip HEAD while we're at it :)

[Sebastian Noack, 2015/05/06 15:17:56]

Yeah, realized that as well, but slightly preferred to not check for end of line
to keep assumptions as small as possible, in case the output changes in future
versions or dependent on configuration. However, it doesn't matter much. So LGTM
either with or without matching end of line.

+      remote, local = match.groups()
+      with open(os.devnull, "wb") as devnull:
+        if subprocess.call(["git", "branch", "--track", local, remote],
+                           cwd=repo, stdout=devnull, stderr=devnull) == 0:
+          newly_tracked = True
+    # Finally fetch any newly tracked remote branches
+    if newly_tracked:
+      subprocess.check_call(["git", "fetch", "--quiet", "origin"], cwd=repo)
 
   def update(self, repo, rev):
     subprocess.check_call(["git", "checkout", "--quiet", rev], cwd=repo)