Fix broken bash completion of local refs.

Commit 35e65ecc broke completion of local refs, e.g. "git pull . fo<tab>"
no longer would complete to "foo".  Instead it printed out an internal
git error ("fatal: Not a git repository: '.'").

The break occurred when I tried to improve performance by switching from
git-peek-remote to git-for-each-ref.  Apparently git-peek-remote will
drop into directory "$1/.git" (where $1 is its first parameter) if it
is given a repository with a working directory.  This allowed the bash
completion code to work properly even though it was not handing over
the true repository directory.

So now we do a stat in bash to see if we need to add "/.git" to the
path string before running any command with --git-dir.

I also tried to optimize away two "git rev-parse --git-dir" invocations
in common cases like "git log fo<tab>" as typically the user is in the
top level directory of their project and therefore the .git subdirectory
is in the current working directory.  This should make a difference on
systems where fork+exec might take a little while.
Signed-off-by: NShawn O. Pearce <spearce@spearce.org>
Signed-off-by: NJunio C Hamano <junkio@cox.net>

contrib/completion/git-completion.bash

@@ -34,7 +34,19 @@
 
 __gitdir ()
 {
-	echo "${__git_dir:-$(git rev-parse --git-dir 2>/dev/null)}"
+	if [ -z "$1" ]; then
+		if [ -n "$__git_dir" ]; then
+			echo "$__git_dir"
+		elif [ -d .git ]; then
+			echo .git
+		else
+			git rev-parse --git-dir 2>/dev/null
+		fi
+	elif [ -d "$1/.git" ]; then
+		echo "$1/.git"
+	else
+		echo "$1"
+	fi
 }
 
 __git_ps1 ()
@@ -51,7 +63,7 @@ __git_ps1 ()
 
 __git_heads ()
 {
-	local cmd i is_hash=y dir="${1:-$(__gitdir)}"
+	local cmd i is_hash=y dir="$(__gitdir "$1")"
 	if [ -d "$dir" ]; then
 		for i in $(git --git-dir="$dir" \
 			for-each-ref --format='%(refname)' \
@@ -60,7 +72,7 @@ __git_heads ()
 		done
 		return
 	fi
-	for i in $(git-ls-remote "$dir" 2>/dev/null); do
+	for i in $(git-ls-remote "$1" 2>/dev/null); do
 		case "$is_hash,$i" in
 		y,*) is_hash=n ;;
 		n,*^{}) is_hash=y ;;
@@ -72,7 +84,7 @@ __git_heads ()
 
 __git_refs ()
 {
-	local cmd i is_hash=y dir="${1:-$(__gitdir)}"
+	local cmd i is_hash=y dir="$(__gitdir "$1")"
 	if [ -d "$dir" ]; then
 		if [ -e "$dir/HEAD" ]; then echo HEAD; fi
 		for i in $(git --git-dir="$dir" \
@@ -101,20 +113,9 @@ __git_refs ()
 
 __git_refs2 ()
 {
-	local cmd i is_hash=y dir="${1:-$(__gitdir)}"
-	if [ -d "$dir" ]; then
-		cmd=git-peek-remote
-	else
-		cmd=git-ls-remote
-	fi
-	for i in $($cmd "$dir" 2>/dev/null); do
-		case "$is_hash,$i" in
-		y,*) is_hash=n ;;
-		n,*^{}) is_hash=y ;;
-		n,refs/tags/*) is_hash=y; echo "${i#refs/tags/}:${i#refs/tags/}" ;;
-		n,refs/heads/*) is_hash=y; echo "${i#refs/heads/}:${i#refs/heads/}" ;;
-		n,*) is_hash=y; echo "$i:$i" ;;
-		esac
+	local i
+	for i in $(__git_refs "$1"); do
+		echo "$i:$i"
 	done
 }