Revert "completion: fix shell expansion of items"

This reverts commit 25ae7cf.

That patch does fix expansion of weird variables in some
simple tests, but it also seems to break other things, like
expansion of refs by "git checkout".

While we're sorting out the correct solution, we are much
better with the original bug (people with metacharacters in
their completions occasionally see an error message) than
the current bug (ref completion does not work at all).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

contrib/completion/git-completion.bash

@@ -225,13 +225,6 @@ _get_comp_words_by_ref ()
 fi
 fi
 
-# Quotes the argument for shell reuse
-__git_quote()
-{
-	local quoted=${1//\'/\'\\\'\'}
-	printf "'%s'" "$quoted"
-}
-
 # Generates completion reply with compgen, appending a space to possible
 # completion words, if necessary.
 # It accepts 1 to 4 arguments:
@@ -268,7 +261,7 @@ __gitcomp ()
 __gitcomp_nl ()
 {
 	local IFS=$'\n'
-	COMPREPLY=($(compgen -P "${2-}" -S "${4- }" -W "$(__git_quote "$1")" -- "${3-$cur}"))
+	COMPREPLY=($(compgen -P "${2-}" -S "${4- }" -W "$1" -- "${3-$cur}"))
 }
 
 __git_heads ()