Download latest patch when no patch is specified

When someone does "repo download -c <project> <change>"
without specifying a patch number, by default patch 1 is
downloaded. An alternative is to look for the latest patch
and download the same when no explicit patch is given.
This commit does the same by identifying the latest patch
using "git ls-remote".

Change-Id: Ia5fa7364415f53a3d9436df4643e38f3c90ded58

2 files changed, 18 insertions, 0 deletions

diff --git a/project.py b/project.py
index e4682e6a..5297a5cb 100644..100755
--- a/project.py
+++ b/project.py
@@ -2270,6 +2270,16 @@ class Project(object):
       if self._allrefs:
         raise GitError('%s cherry-pick %s ' % (self.name, rev))
 
+  def _LsRemote(self):
+    cmd = ['ls-remote']
+    p = GitCommand(self, cmd, capture_stdout=True)
+    if p.Wait() == 0:
+      if hasattr(p.stdout, 'decode'):
+        return p.stdout.decode('utf-8')
+      else:
+        return p.stdout
+    return None
+
   def _Revert(self, rev):
     cmd = ['revert']
     cmd.append('--no-edit')
diff --git a/subcmds/download.py b/subcmds/download.py
index e1010aa2..384af781 100644..100755
--- a/subcmds/download.py
+++ b/subcmds/download.py
@@ -62,6 +62,14 @@ If no project is specified try to use current directory as a project.
           ps_id = int(m.group(2))
         else:
           ps_id = 1
+          regex = r'refs/changes/%2.2d/%d/(\d+)' % (chg_id % 100, chg_id)
+          output = project._LsRemote()
+          if output:
+            rcomp = re.compile(regex, re.I)
+            for line in output.splitlines():
+              match = rcomp.search(line)
+              if match:
+                ps_id = max(int(match.group(1)), ps_id)
         to_get.append((project, chg_id, ps_id))
       else:
         project = self.GetProjects([a])[0]