Merge branch 'kn/for-each-branch'

Using the timestamp based criteria in "git branch --sort" did not
tiebreak branches that point at commits with the same timestamp (or
the same commit), making the resulting output unstable.

* kn/for-each-branch:
ref-filter: fallback on alphabetical comparison

diff --cc ref-filter.c
Simple merge

diff --cc t/t3203-branch-output.sh
Simple merge