Merge branch 'js/for-each-repo-keep-going'

A scheduled "git maintenance" job is expected to work on all
repositories it knows about, but it stopped at the first one that
errored out.  Now it keeps going.

* js/for-each-repo-keep-going:
  maintenance: running maintenance should not stop on errors
  for-each-repo: optionally keep going on an error

diff --cc builtin/gc.c
Simple merge