Make _strptime.TimeRE().pattern() use ``\s+`` for matching whitespace instead
of ``\s*``.  This prevents patterns from "stealing" bits from other patterns in
order to make a match work.

Closes bug #1730389.  Will be backported.
diff --git a/Lib/_strptime.py b/Lib/_strptime.py
index 9e7823a..166cf82 100644
--- a/Lib/_strptime.py
+++ b/Lib/_strptime.py
@@ -250,7 +250,7 @@
         regex_chars = re_compile(r"([\\.^$*+?\(\){}\[\]|])")
         format = regex_chars.sub(r"\\\1", format)
         whitespace_replacement = re_compile('\s+')
-        format = whitespace_replacement.sub('\s*', format)
+        format = whitespace_replacement.sub('\s+', format)
         while '%' in format:
             directive_index = format.index('%')+1
             processed_format = "%s%s%s" % (processed_format,
diff --git a/Lib/test/test_strptime.py b/Lib/test/test_strptime.py
index f474752..92c722a 100644
--- a/Lib/test/test_strptime.py
+++ b/Lib/test/test_strptime.py
@@ -190,6 +190,15 @@
                         "locale data that contains regex metacharacters is not"
                         " properly escaped")
 
+    def test_whitespace_substitution(self):
+        # When pattern contains whitespace, make sure it is taken into account
+        # so as to not allow to subpatterns to end up next to each other and
+        # "steal" characters from each other.
+        pattern = self.time_re.pattern('%j %H')
+        self.failUnless(not re.match(pattern, "180"))
+        self.failUnless(re.match(pattern, "18 0"))
+
+
 class StrptimeTests(unittest.TestCase):
     """Tests for _strptime.strptime."""