make_py_package: don't mutate dep_artifacts

Summary: mutating dep_artifact like this causes it to grow between invocations of `_pex_modules_args`. This causes bytecodes to accumulate unnecessarily for different subtargets.

Reviewed By: IanChilds

Differential Revision: D64465025

fbshipit-source-id: 6a12a9bab4cf6279607ede2a6d7f01b3c77f8b27

python/make_py_package.bzl

@@ -647,7 +647,7 @@ def _pex_modules_args(
     if pex_modules.compile:
         pyc_mode = PycInvalidationMode("UNCHECKED_HASH") if symlink_tree_path == None else PycInvalidationMode("CHECKED_HASH")
         bytecode_manifests = pex_modules.manifests.bytecode_manifests(pyc_mode)
-        dep_artifacts.extend([a[0] for a in pex_modules.manifests.bytecode_artifacts_with_paths(pyc_mode)])
+        dep_artifacts = dep_artifacts + [a[0] for a in pex_modules.manifests.bytecode_artifacts_with_paths(pyc_mode)]
 
         bytecode_manifests_path = ctx.actions.write(
             "__bytecode_manifests{}.txt".format(output_suffix),