fix: fetch base branch before performing merge-base

Also make sure the copright script honors the refspec that's passed on
it's command line.

Signed-off-by: Harrison Mutai <harrison.mutai@arm.com>
Signed-off-by: Tomás González <tomasagustin.gonzalezorlando@arm.com>
Change-Id: I91250c39015129c3c1eef0891ff55ee2ea6f74b1
3 files changed