Fix distutils.filelist.FileList under Windows (#13193).

The code used to call os.path.join to build a regex but without escaping
the backslash, which lead to test failures on Windows.  Antoine Pitrou
fixed it in 0a94e2f807c7 by enhancing the code to accept both / and \,
with proper escaping, but in my opinion this goes against the distutils
feature freeze, hence this change.

Lib/distutils/filelist.py

@@ -313,10 +313,8 @@ def translate_pattern(pattern, anchor=1, prefix=None, is_regex=0):
         # ditch end of pattern character
         empty_pattern = glob_to_re('')
         prefix_re = (glob_to_re(prefix))[:-len(empty_pattern)]
-        # match both path separators, as in Postel's principle
-        sep_pat = "[" + re.escape(os.path.sep + os.path.altsep
-                                  if os.path.altsep else os.path.sep) + "]"
-        pattern_re = "^" + sep_pat.join([prefix_re, ".*" + pattern_re])
+        # paths should always use / in manifest templates
+        pattern_re = "^%s/.*%s" % (prefix_re, pattern_re)
     else:                               # no prefix -- respect anchor flag
         if anchor:
             pattern_re = "^" + pattern_re

Misc/NEWS

@@ -282,8 +282,7 @@ Library
 - Issues #1745761, #755670, #13357, #12629, #1200313: HTMLParser now correctly
   handles non-valid attributes, including adjacent and unquoted attributes.
 
-- Issue #13193: Fix distutils.filelist.FileList under Windows.  The
-  "recursive-include" directive now recognizes both legal path separators.
+- Issue #13193: Fix distutils.filelist.FileList under Windows.
 
 - Issue #13384: Remove unnecessary __future__ import in Lib/random.py