Support tagging versions locally

Change-Id: I812c1e06700346d99e2cd4a84b198c3e52fd8ec9
diff --git a/tools/historic_run.py b/tools/historic_run.py
index 9822648..1124f95 100755
--- a/tools/historic_run.py
+++ b/tools/historic_run.py
@@ -76,9 +76,11 @@
 
 
 def git_commit_from_hash(hash):
+    # If there is a tag for the given commit then the commit timestamp is on the
+    # last line.
     commit_timestamp_str = subprocess.check_output(
         ['git', 'show', '--no-patch', '--no-notes', '--pretty=%ct',
-         hash]).decode('utf-8').strip()
+         hash]).decode('utf-8').strip().splitlines()[-1]
     commit_timestamp = int(commit_timestamp_str)
     destination_dir = '%s/%s/' % (MASTER_COMMITS, hash)
     destination = '%s%s' % (destination_dir, 'r8.jar')