Merge branch 'nd/grep-true-path' into maint

"git grep -e pattern <tree>" asked the attribute system to read
"<tree>:.gitattributes" file in the working tree, which was
nonsense.

* nd/grep-true-path:
  grep: stop looking at random places for .gitattributes

diff --cc builtin/grep.c
Simple merge

diff --cc grep.c
Simple merge

diff --cc grep.h
Simple merge