Fix an inaccuracy in the comment
diff --git a/Lib/mailbox.py b/Lib/mailbox.py
index 1834177..6264394 100755
--- a/Lib/mailbox.py
+++ b/Lib/mailbox.py
@@ -137,8 +137,8 @@
# _search_end() may not be completely correct, because it doesn't check
# that the two characters preceding "From " are \n\n or the beginning of
# the file. Fixing this would require a more extensive rewrite than is
- # necessary. For convenience, we've added a StrictUnixMailbox class which
- # uses the older, more strict _fromlinepattern regular expression.
+ # necessary. For convenience, we've added a PortableUnixMailbox class
+ # which uses the more lenient _fromlinepattern regular expression.
_fromlinepattern = r"From \s*[^\s]+\s+\w\w\w\s+\w\w\w\s+\d?\d\s+" \
r"\d?\d:\d\d(:\d\d)?(\s+[^\s]+)?\s+\d\d\d\d\s*$"