Merge branch 'cb/path-owner-check-with-sudo'

With a recent update to refuse access to repositories of other
people by default, "sudo make install" and "sudo git describe"
stopped working.  This series intends to loosen it while keeping
the safety.

* cb/path-owner-check-with-sudo:
  t0034: add negative tests and allow git init to mostly work under sudo
  git-compat-util: avoid failing dir ownership checks if running privileged
  t: regression git needs safe.directory when using sudo

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>