use the LWN weekly publication date

Bulk conversion (unfortunately) is a frequent thing when catching up
after a holiday or crontab breakage. It is really annoying figuring out
the LWN weekly edition reading order if they all have the same title
based on the conversion date.

Falls back to the current date if the date cannot be parsed.

recipes/lwn_weekly.recipe

@@ -10,8 +10,21 @@ lwn.net
 
 import re
 import sys
-
+from contextlib import contextmanager
+import locale
+from datetime import datetime
 from calibre.web.feeds.news import BasicNewsRecipe
+from calibre.utils.date import now as nowf
+
+
+@contextmanager
+def temporary_locale(temp_locale):
+    old_locale = locale.getlocale()
+    try:
+        locale.setlocale(locale.LC_ALL, temp_locale)
+        yield
+    finally:
+        locale.setlocale(locale.LC_ALL, old_locale)[2]
 
 
 class WeeklyLWN(BasicNewsRecipe):
@@ -82,6 +95,9 @@ class WeeklyLWN(BasicNewsRecipe):
 
         return url
 
+    def publication_date(self):
+        return self.pub_date
+
     def parse_index(self):
         past_edition = self.recipe_specific_options.get('issue')
         if past_edition and isinstance(past_edition, str):
@@ -91,6 +107,15 @@ class WeeklyLWN(BasicNewsRecipe):
         else:
             index_url = self.print_version('/free/bigpage')
         soup = self.index_to_soup(index_url)
+
+        try:
+            with temporary_locale('en_US'):
+                date_match = re.match(r'.* +for +(.*) +\[.*', self.tag_to_string(soup.head.title.string))
+                self.pub_date = datetime.strptime(date_match[1], '%B %d, %Y')
+        except (TypeError, ValueError):
+            self.log.error('Failed to parse publication date from title: %r, using current time' % soup.head.title.string)
+            self.pub_date = nowf()
+
         curr = soup.body
 
         articles = {}