Merge branch 'jk/shallow-update-fix'

Serving objects from a shallow repository needs to write a
new file to hold the temporary shallow boundaries but it was not
cleaned when we exit due to die() or a signal.

* jk/shallow-update-fix:
  shallow: verify shallow file after taking lock
  shallow: automatically clean up shallow tempfiles
  shallow: use stat_validity to check for up-to-date file

diff --cc fetch-pack.c
Simple merge

diff --cc upload-pack.c
Simple merge