Merge branch 'dk/stash-apply-index'
The stash.index configuration variable can be set to make "git stash
pop/apply" pretend that it was invoked with "--index".
* dk/stash-apply-index:
stash: honor stash.index in apply, pop modes
stash: refactor private config globals
t3905: remove unneeded blank line
t3903: reduce dependencies on previous tests