Blacklist http(s): from being parsed as a git footer

It's unlikely that anyone would ever intend to have a git trailer
whose key is "http", but since URLs are often long, it is rather
likely that someone would put a URL on a line all by itself. When
that happens, don't accidentally interpret it as a footer.

R=iannucci, tandrii

Bug: 766234
Change-Id: I3101119c4e49e20339487618cc1719452b026d90
Reviewed-on: https://chromium-review.googlesource.com/849484
Commit-Queue: Aaron Gable <agable@chromium.org>
Reviewed-by: Andrii Shyshkalov <tandrii@chromium.org>
diff --git a/git_footers.py b/git_footers.py
index 3f12d17..92c7dab 100755
--- a/git_footers.py
+++ b/git_footers.py
@@ -15,6 +15,7 @@
 
 FOOTER_PATTERN = re.compile(r'^\s*([\w-]+): *(.*)$')
 CHROME_COMMIT_POSITION_PATTERN = re.compile(r'^([\w/\-\.]+)@{#(\d+)}$')
+FOOTER_KEY_BLACKLIST = set(['http', 'https'])
 
 
 def normalize_name(header):
@@ -24,10 +25,9 @@
 def parse_footer(line):
   """Returns footer's (key, value) if footer is valid, else None."""
   match = FOOTER_PATTERN.match(line)
-  if match:
+  if match and match.group(1) not in FOOTER_KEY_BLACKLIST:
     return (match.group(1), match.group(2))
-  else:
-    return None
+  return None
 
 
 def parse_footers(message):