Merge bug fixes into release

[NKID00]

#1009 #1188 fixed the date formatting bug in the master branch. However the same bug still exists in the latest release and caused malfunction of my server.

master:

• bottle/bottle.py

  Lines 2911 to 2912 in f9b1849

  	headers['Last-Modified'] = email.utils.formatdate(stats.st_mtime,
  	usegmt=True)

• bottle/bottle.py

  Line 2913 in f9b1849

  headers['Date'] = email.utils.formatdate(time.time(), usegmt=True)

• bottle/bottle.py

  Line 1888 in f9b1849

  value = http_date(value)

release-0.12:

• bottle/bottle.py

  Lines 2499 to 2500 in 1522198

  	lm = time.strftime("%a, %d %b %Y %H:%M:%S GMT", time.gmtime(stats.st_mtime))
  	headers['Last-Modified'] = lm

• bottle/bottle.py

  Line 2506 in 1522198

  headers['Date'] = time.strftime("%a, %d %b %Y %H:%M:%S GMT", time.gmtime())

• bottle/bottle.py

  Line 1648 in 1522198

  value = time.strftime("%a, %d %b %Y %H:%M:%S GMT", value)

Is it possible to merge these bug fixes (and also other bug fixes which haven't been merged) into the release branch?

Or should I use the master branch in a production-grade server in order to get the bug fixed?

[oz123]

@NKID00 I have been using the master branch for like 4 years now in production.. Never had a problem.
Bottle is quite well tested 💪

[NKID00]

@oz123 Thanks. The server using the master branch is working just fine now.