commit-msg: Fix jumbling of URL at end of message

If a commit message has a URL (e.g. http://) at the start of the
last line of the message the commit-msg hook was confusing it as
a footer line, and inserted the Change-Id before it.

Test for URLs at the start of the line and don't consider them to
be message footers.

Bug: issue 531
Change-Id: Iba4902502b4f154f456b6b3511b6f3b6cc0b3129
Signed-off-by: Shawn O. Pearce <sop@google.com>
2 files changed