revert addition of narrow_relative_paths()

src/python/pants/build_graph/target.py

@@ -26,7 +26,6 @@
 from pants.source.payload_fields import SourcesField
 from pants.source.wrapped_globs import Files, FilesetWithSpec, Globs
 from pants.subsystem.subsystem import Subsystem
-from pants.util.dirutil import narrow_relative_paths
 from pants.util.memo import memoized_property
 
 
@@ -502,15 +501,20 @@ def sources_relative_to_buildroot(self):
     """
     :API: public
     """
-    return self._sources_field.relative_to_buildroot()
+    if self.has_sources():
+      return self._sources_field.relative_to_buildroot()
+    else:
+      return []
 
   def sources_relative_to_source_root(self):
     """
     :API: public
     """
-    buildroot = get_buildroot()
-    abs_source_root = os.path.join(get_buildroot(), self.target_base)
-    return narrow_relative_paths(buildroot, abs_source_root, self.sources_relative_to_buildroot())
+    if self.has_sources():
+      abs_source_root = os.path.join(get_buildroot(), self.target_base)
+      for source in self.sources_relative_to_buildroot():
+        abs_source = os.path.join(get_buildroot(), source)
+        yield os.path.relpath(abs_source, abs_source_root)
 
   def globs_relative_to_buildroot(self):
     """

src/python/pants/util/dirutil.py

@@ -500,10 +500,3 @@ def split_basename_and_dirname(path):
   if not os.path.isfile(path):
     raise ValueError("{} does not exist or is not a regular file.".format(path))
   return (os.path.dirname(path), os.path.basename(path))
-
-
-def narrow_relative_paths(cur_root_dir, new_root_subdir, rel_paths):
-  """If `cur_root_dir` contains `new_root_subdir`, relativize `rel_paths` to `new_root_subdir`."""
-  for rel_file in rel_paths:
-    file_abs = os.path.join(cur_root_dir, rel_file)
-    yield os.path.relpath(file_abs, new_root_subdir)