Merge branch 'maint-1.6.2' into maint

* maint-1.6.2:
  base85: Make the code more obvious instead of explaining the non-obvious
  base85: encode_85() does not use the decode table
  base85 debug code: Fix length byte calculation
  checkout -m: do not try to fall back to --merge from an unborn branch

Conflicts:
	diff.c

diff --cc base85.c
Simple merge

diff --cc builtin-checkout.c
Simple merge