From patchwork Sun May 21 20:48:03 2017
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Subject: [8, of, 8,
 demandimport-py3] python3: allow hgloader to work with lazy loaders
From: Siddharth Agarwal <sid0@fb.com>
X-Patchwork-Id: 20802
Message-Id: <902d8e08f7e5bc6114e2.1495399683@devvm31800.prn1.facebook.com>
To: <mercurial-devel@mercurial-scm.org>
Date: Sun, 21 May 2017 13:48:03 -0700

# HG changeset patch
# User Siddharth Agarwal <sid0@fb.com>
# Date 1495398377 25200
#      Sun May 21 13:26:17 2017 -0700
# Node ID 902d8e08f7e5bc6114e2fd9285be6ef75225da9e
# Parent  1bf07f6a0c323a4a842d7e76d14e4e893a2b68ca
python3: allow hgloader to work with lazy loaders

Don't clobber the loader returned from find_spec.

This brings `hg version` down from 0.27 seconds to 0.17.

diff --git a/mercurial/__init__.py b/mercurial/__init__.py
--- a/mercurial/__init__.py
+++ b/mercurial/__init__.py
@@ -53,7 +53,14 @@ if sys.version_info[0] >= 3:
 
             # TODO need to support loaders from alternate specs, like zip
             # loaders.
-            spec.loader = hgloader(spec.name, spec.origin)
+            loader = hgloader(spec.name, spec.origin)
+            # Can't use util.safehasattr here because that would require
+            # importing util, and we're in import code.
+            if hasattr(spec.loader, 'loader'): # hasattr-py3-only
+                # This is a nested loader (maybe a lazy loader?)
+                spec.loader.loader = loader
+            else:
+                spec.loader = loader
             return spec
 
     def replacetokens(tokens, fullname):