config: correct '**' matching in includeIf patterns

The current wildmatch() call for includeIf's gitdir pattern does not
pass the WM_PATHNAME flag. Without this flag, '*' is treated _almost_
the same as '**' (because '*' also matches slashes) with one exception:

'/**/' can match a single slash. The pattern 'foo/**/bar' matches
'foo/bar'.

But '/*/', which is essentially what wildmatch engine sees without
WM_PATHNAME, has to match two slashes (and '*' matches nothing). Which
means 'foo/*/bar' cannot match 'foo/bar'. It can only match 'foo//bar'.

The result of this is the current wildmatch() call works most of the
time until the user depends on '/**/' matching no path component. And
also '*' matches slashes while it should not, but people probably
haven't noticed this yet. The fix is straightforward.

Reported-by: Jason Karns <jason.karns@gmail.com>
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

config.c

@@ -242,7 +242,7 @@ static int include_by_gitdir(const struct config_options *opts,
 	}
 
 	ret = !wildmatch(pattern.buf + prefix, text.buf + prefix,
-			 icase ? WM_CASEFOLD : 0);
+			 WM_PATHNAME | (icase ? WM_CASEFOLD : 0));
 
 	if (!ret && !already_tried_absolute) {
 		/*

t/t1305-config-include.sh

@@ -229,6 +229,19 @@ test_expect_success 'conditional include, early config reading' '
 	)
 '
 
+test_expect_success 'conditional include with /**/' '
+	REPO=foo/bar/repo &&
+	git init $REPO &&
+	cat >>$REPO/.git/config <<-\EOF &&
+	[includeIf "gitdir:**/foo/**/bar/**"]
+	path=bar7
+	EOF
+	echo "[test]seven=7" >$REPO/.git/bar7 &&
+	echo 7 >expect &&
+	git -C $REPO config test.seven >actual &&
+	test_cmp expect actual
+'
+
 test_expect_success SYMLINKS 'conditional include, set up symlinked $HOME' '
 	mkdir real-home &&
 	ln -s real-home home &&