Merge branch 'jh/checkout-auto-tracking'

Merge branch 'jh/checkout-auto-tracking'

Fix a minor regression in v1.8.3.2 and later that made it
impossible to base your local work on anything but a local branch
of the upstream repository you are tracking from.

* jh/checkout-auto-tracking:
  t3200: fix failure on case-insensitive filesystems
  branch.c: Relax unnecessary requirement on upstream's remote ref name
  t3200: Add test demonstrating minor regression in 41c21f2
  Refer to branch.<name>.remote/merge when documenting --track
  t3200: Minor fix when preparing for tracking failure
  t2024: Fix &&-chaining and a couple of typos