Use accurate line numbers for the commit message

We used a magic number matching the most common use-case, we now compute
the offset based on the way Gerrit generates the COMMIT_MSG.

Change-Id: Ieb5e5e199beb122336cf3a7568d0313049aa0f57
2 files changed
tree: 46c832150d7c0ccd79c4843aa59ba4ca4086f090
  1. LICENSE
  2. README
  3. checkstyle/
  4. cmd/
  5. creds/
  6. gerrit/
  7. git/
  8. jenkins/
  9. lint/