Refine #190 (#191)

Even though the provided test case did work for situations where files
had mismatching directory names, it didn't work well if one of the
directory names was the prefix of the other.

examples/BUILD

@@ -291,3 +291,12 @@ jsonnet_to_json(
         "nested/dir2/file2.json",
     ],
 )
+
+jsonnet_to_json(
+    name = "multiple_outs_nested_asymmetric",
+    src = "multiple_outs_nested_asymmetric.jsonnet",
+    outs = [
+        "multiple_outs_nested_asymmetric/aaaaa/file.json",
+        "multiple_outs_nested_asymmetric/file.json",
+    ],
+)

examples/multiple_outs_nested_asymmetric.jsonnet

@@ -0,0 +1,4 @@
+{
+  'aaaaa/file.json': {},
+  'file.json': {},
+}

jsonnet/jsonnet.bzl

@@ -242,7 +242,9 @@ def _jsonnet_to_json_impl(ctx):
         # directory name that is shared by all output files.
         base_dirname = ctx.outputs.outs[0].dirname.split("/")
         for output in ctx.outputs.outs[1:]:
-            for i, (part1, part2) in enumerate(zip(base_dirname, output.dirname.split("/"))):
+            component_pairs = zip(base_dirname, output.dirname.split("/"))
+            base_dirname = base_dirname[:len(component_pairs)]
+            for i, (part1, part2) in enumerate(component_pairs):
                 if part1 != part2:
                     base_dirname = base_dirname[:i]
                     break