42cf7191e3
git commit calls the commit-msg hook when the user creates an empty message file in order to abort the commit process. If the hook then edits the file content and inserts a line, such as our Change-Id, git takes this as a valid commit and creates it, rather than aborts. Thus we need to test for the empty file case specially and avoid creating a Change-Id line during it. Change-Id: I84a6309ae91d04b489ba48587936bfa80ad04dc1 Signed-off-by: Shawn O. Pearce <sop@google.com>