Merge branch 'jc/maint-blame-no-such-path'

"git blame MAKEFILE" run in a history that has "Makefile" but not "MAKEFILE" should say "No such file MAKEFILE in HEAD", but got confused on a case insensitive filesystem and failed to do so. Even during a conflicted merge, "git blame $path" always meant to blame uncommitted changes to the "working tree" version; make it more useful by showing cleanly merged parts as coming from the other branch that is being merged. * jc/maint-blame-no-such-path: blame: allow "blame file" in the middle of a conflicted merge blame $path: avoid getting fooled by case insensitive filesystems