A packed reference can be overridden by a loose reference, in which
case the packed reference is obsolete and is never used. The object
pointed to by such a reference can be garbage collected. Since
d66da478f2, this could lead to the emission of a spurious error
message:
error: refs/heads/master does not point to a valid object!
The error is generated by repack_without_ref() if there is an obsolete
dangling packed reference in packed-refs when the packed-refs file has
to be rewritten due to the deletion of another packed reference. Add
a failing test demonstrating this problem and some passing tests of
related scenarios.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>