git-clean: honor core.excludesfile

git-clean did not honor core.excludesfile configuration
variable, although some other commands such as git-add and
git-status did.  Fix this inconsistency.

Original report and patch from Shun'ichi Fuji.  Rewritten by me
and bugs and tests are mine.
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

git-clean.sh

@@ -75,15 +75,22 @@ esac
 
 if [ -z "$ignored" ]; then
 	excl="--exclude-per-directory=.gitignore"
+	excl_info= excludes_file=
 	if [ -f "$GIT_DIR/info/exclude" ]; then
 		excl_info="--exclude-from=$GIT_DIR/info/exclude"
 	fi
+	if cfg_excl=$(git config core.excludesfile) && test -f "$cfg_excl"
+	then
+		excludes_file="--exclude-from=$cfg_excl"
+	fi
 	if [ "$ignoredonly" ]; then
 		excl="$excl --ignored"
 	fi
 fi
 
-git ls-files --others --directory $excl ${excl_info:+"$excl_info"} -- "$@" |
+git ls-files --others --directory \
+	$excl ${excl_info:+"$excl_info"} ${excludes_file:+"$excludes_file"} \
+	-- "$@" |
 while read -r file; do
 	if [ -d "$file" -a ! -L "$file" ]; then
 		if [ -z "$cleandir" ]; then

t/t7300-clean.sh

@@ -177,4 +177,15 @@ test_expect_success 'clean.requireForce and -f' '
 
 '
 
+test_expect_success 'core.excludesfile' '
+
+	echo excludes >excludes &&
+	echo included >included &&
+	git config core.excludesfile excludes &&
+	output=$(git clean -n excludes included 2>&1) &&
+	expr "$output" : ".*included" >/dev/null &&
+	! expr "$output" : ".*excludes" >/dev/null
+
+'
+
 test_done