Issue #13193: Fix distutils.filelist.FileList and

packaging.manifest.Manifest under Windows.  The "recursive-include"
directive now recognizes both legal path separators.

Lib/distutils/filelist.py

@@ -313,7 +313,10 @@ 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)]
-        pattern_re = "^" + os.path.join(prefix_re, ".*" + pattern_re)
+        # 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])
     else:                               # no prefix -- respect anchor flag
         if anchor:
             pattern_re = "^" + pattern_re

Lib/packaging/manifest.py

@@ -366,7 +366,10 @@ def _translate_pattern(pattern, anchor=True, prefix=None, is_regex=False):
         # ditch end of pattern character
         empty_pattern = _glob_to_re('')
         prefix_re = _glob_to_re(prefix)[:-len(empty_pattern)]
-        pattern_re = "^" + os.path.join(prefix_re, ".*" + pattern_re)
+        # 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])
     else:                               # no prefix -- respect anchor flag
         if anchor:
             pattern_re = "^" + pattern_re

Misc/NEWS

@@ -365,6 +365,10 @@ Core and Builtins
 Library
 -------
 
+- Issue #13193: Fix distutils.filelist.FileList and
+  packaging.manifest.Manifest under Windows.  The "recursive-include"
+  directive now recognizes both legal path separators.
+
 - Issue #13384: Remove unnecessary __future__ import in Lib/random.py
 
 - Issue #13149: Speed up append-only StringIO objects.