Merge branch 'jk/remote-tracking-ref-leakfix'

Leakfix.

* jk/remote-tracking-ref-leakfix:
  remote: always allocate branch.push_tracking_ref
  remote: fix leak in branch_get_push_1() with invalid "simple" config
  remote: drop const return of tracking_for_push_dest()
  remote: return non-const pointer from error_buf()

diff --cc remote.c
Simple merge

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