Auto merge of #39055 - aidanhs:aphs-deinit-before-init, r=alexcrichton

If submodule init fails, try from scratch

See #39051

I wonder if the cause could be some strange not-quite-checked-out state in a submodule. Try and fix this by force deinitialising everything before initialising (this will not throw away downloaded objects, git will skip them on the next attempt at cloning).

r? @alexcrichton

diff --cc .travis.yml
Simple merge