Merge branch 'jk/ref-filter-segfault-fix'

A NULL-dereference bug has been corrected in an error codepath in
"git for-each-ref", "git branch --list" etc.

* jk/ref-filter-segfault-fix:
  ref-filter: fix NULL check for parse object failure

diff --cc ref-filter.c
Simple merge

diff --cc t/t6300-for-each-ref.sh
Simple merge