[PATCH 1 of 3] py3: silence warning about deprecation of imp module

[Yuya Nishihara]

# HG changeset patch
# User Yuya Nishihara <yuya at tcha.org>
# Date 1523074919 -32400
#      Sat Apr 07 13:21:59 2018 +0900
# Node ID 5f401721fa2a4ba1e5b5ea570c9c0978481a20f7
# Parent  a0d71618074f3c90180b4e6615544ab20b2cdda4
py3: silence warning about deprecation of imp module

Well, we could fix that, but we aren't yet to reach the state caring about
deprecation on the Python 3 line. So let's silence it for now to fix tons
of "minor" Py2/3 incompatibilities by relying on our test suite.

diff --git a/mercurial/util.py b/mercurial/util.py
--- a/mercurial/util.py
+++ b/mercurial/util.py
@@ -194,6 +194,9 @@ if _dowarn and pycompat.ispy3:
                             r'mercurial')
     warnings.filterwarnings(r'ignore', r'invalid escape sequence',
                             DeprecationWarning, r'mercurial')
+    # TODO: reinvent imp.is_frozen()
+    warnings.filterwarnings(r'ignore', r'the imp module is deprecated',
+                            DeprecationWarning, r'mercurial')
 
 def nouideprecwarn(msg, version, stacklevel=1):
     """Issue an python native deprecation warning