for-each-ref: skip and warn about broken ref names
for-each-ref: skip and warn about broken ref names

Print a warning message for any bad ref names we find in the repo and
skip them so callers don't have to deal with parsing them.

It might be useful in the future to have a flag where we would not
skip these refs for those callers that want to and are prepared (for
example by using a --format argument with %0 as a delimiter after the
ref name).

Signed-off-by: Ronnie Sahlberg <2cb6c6c4ccf58d41468189c2307f7a4ebf120324@google.com>
Signed-off-by: Jonathan Nieder <b57189c5f2fd5b3daf3350a77fde90def1080fa5@gmail.com>
Signed-off-by: Junio C Hamano <a6723cc3f76163bf7adb636a73ac3b0ceb3e6b9b@pobox.com>

destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git