Automated rollback of commit a1c9f8d33457cd1f3b01299863bcab2667c13a52.

*** Reason for rollback ***

PY3 does not support Python proto1.

*** Original change description ***

Automated rollback of commit 4c72a82ada742bd369185cd07c57f96c497ce440.

*** Reason for rollback ***

Breaks, at least, //ads/aswan/tools:format_mr_results.

*** Original change description ***

Remove python3/ prefix to generated .pyc files.

That makes:
(a) merging PY2 and PY3 .runfiles impossible (which is incorrect anyway) and
(b) generated .py source files incompatible with 2to3 (src_version=PY2) - that's OK as we deprecate 2to3.

RELNOTES: n/a
PiperOrigin-RevId: 200256210
diff --git a/src/main/java/com/google/devtools/build/lib/rules/python/PythonUtils.java b/src/main/java/com/google/devtools/build/lib/rules/python/PythonUtils.java
index 7acd86c..c524a30 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/python/PythonUtils.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/python/PythonUtils.java
@@ -81,14 +81,14 @@
   }
 
   /**
-   * Get the artifact generated by the 2to3 action. The artifact is in a python3
-   * subdirectory to avoid conflicts (eg. when the input file is generated).
+   * Get the artifact generated by the 2to3 action.
+   * (There might be conflicts eg. when the input file is generated, but that case is unsupported
+   *  because 2to3 is obsolete).
    */
   private static Artifact get2to3OutputArtifact(RuleContext ruleContext, Artifact input) {
     ArtifactRoot root =
         ruleContext.getConfiguration().getGenfilesDirectory(ruleContext.getRule().getRepository());
-    PathFragment path = PathFragment.create("python3").getRelative(input.getRootRelativePath());
-    return ruleContext.getShareableArtifact(path, root);
+    return ruleContext.getDerivedArtifact(input.getRootRelativePath(), root);
   }
 
   /**