Merge branch 'kj/renamed-submodule' into jch

The case where a new submodule takes a path where used to be a
completely different subproject is now dealt a bit better than
before.

Comments?

* kj/renamed-submodule:
  submodule: skip redundant active entries when pattern covers path
  submodule: prevent overwriting .gitmodules entry on path reuse

diff --cc builtin/submodule--helper.c
Simple merge