Torstein Hegge [off-list ref] writes:
I was wondering why "git grep show-ref *.sh" gave so few users. It looks
like rev-parse is more common.
It is primarily because show-ref is slightly newer. When you have a
full refname (e.g. refs/bisect/bad) and not an arbitrary object name
that is spelled in a random way (e.g. master~24):
show-ref --verify refs/bisect/bad
is a perfectly valid way to make sure it _is_ an existing ref.
Cf. 358ddb62cfd0 (Add "git show-ref" builtin command, 2006-09-15)