Trivial path optimization test

Linus:
    get_pathspec() does turn '.' into an empty string (which is
    correct - git internally does _not_ ever understand the notion of
    "." as the current working directory), but it doesn't ever do the
    optimization of noticing that a pathspec that consists solely of
    an empty string is "equivalent" to an empty pathspec.

The test is to ensure that this behaviour stays.

Signed-off-by: Alex Riesen <raa.lkml@gmail.com>
Signed-off-by: Junio C Hamano <junkio@cox.net>

t/t6004-rev-list-path-optim.sh

@@ -0,0 +1,19 @@
+#!/bin/sh
+
+test_description='git-rev-list trivial path optimization test'
+
+. ./test-lib.sh
+
+test_expect_success setup '
+echo Hello > a &&
+git add a &&
+git commit -m "Initial commit" a
+'
+
+test_expect_success path-optimization '
+    commit=$(echo "Unchanged tree" | git-commit-tree "HEAD^{tree}" -p HEAD) &&
+    test $(git-rev-list $commit | wc -l) = 2 &&
+    test $(git-rev-list $commit -- . | wc -l) = 1
+'
+
+test_done