Fix rblf_file_exists, it should return true for a directory, too.

Fixes: 184278019
Test: internal
Change-Id: I68c3274a4540dd36e047d6c2027766dbe75d38f8
diff --git a/tools/rbcrun/host.go b/tools/rbcrun/host.go
index 1e43334..b3dd499 100644
--- a/tools/rbcrun/host.go
+++ b/tools/rbcrun/host.go
@@ -118,7 +118,7 @@
 	if err := starlark.UnpackPositionalArgs(b.Name(), args, kwargs, 1, &path); err != nil {
 		return starlark.None, err
 	}
-	if stat, err := os.Stat(path); err != nil || stat.IsDir() {
+	if _, err := os.Stat(path); err != nil {
 		return starlark.False, nil
 	}
 	return starlark.True, nil
diff --git a/tools/rbcrun/testdata/file_ops.star b/tools/rbcrun/testdata/file_ops.star
index e1f1ac2..31631ef 100644
--- a/tools/rbcrun/testdata/file_ops.star
+++ b/tools/rbcrun/testdata/file_ops.star
@@ -4,6 +4,7 @@
 
 def test():
     myname = "file_ops.star"
+    assert.true(rblf_file_exists("."), "./ exists ")
     assert.true(rblf_file_exists(myname), "the file %s does exist" % myname)
     assert.true(not rblf_file_exists("no_such_file"), "the file no_such_file does not exist")
     files = rblf_wildcard("*.star")