submodule: ignore trailing slash in relative url

This is similar to the previous patch, though no user reported a bug and
I could not find a regressive behavior.

However it is a good thing to be strict on the output and for that we
always omit a trailing slash.

Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/t/t0060-path-utils.sh b/t/t0060-path-utils.sh
index 82b98f8..25b48e5 100755
--- a/t/t0060-path-utils.sh
+++ b/t/t0060-path-utils.sh
@@ -319,6 +319,7 @@
 test_submodule_relative_url "../" "foo" "../submodule" "../submodule"
 
 test_submodule_relative_url "(null)" "../foo/bar" "../sub/a/b/c" "../foo/sub/a/b/c"
+test_submodule_relative_url "(null)" "../foo/bar" "../sub/a/b/c/" "../foo/sub/a/b/c"
 test_submodule_relative_url "(null)" "../foo/bar/" "../sub/a/b/c" "../foo/sub/a/b/c"
 test_submodule_relative_url "(null)" "../foo/bar" "../submodule" "../foo/submodule"
 test_submodule_relative_url "(null)" "../foo/submodule" "../submodule" "../foo/submodule"