Backport of 36de2920 from master.

Backport of d6c9bdd8 from master

(the previous commit included only the test)

Backport of 3cba90f2 from master

Backport of 7a7f6fcc from master

Backport of d2f4553d from master

Thanks Paul McMillan, Aymeric Augustin, and Erik Romijn for reviews.

Backport of fd23c060 from master

Backport of 8f621b83 from master.

Backport of c28beb42 from master.

Thanks to linovia for the report.

Backport of 074d3183 from master

Thanks simon29 for the report.

Backport of a8e2ec0e from master

e6ced2bb from master.

Thanks nliberg for the report.

Backport of ca93f02c from master

The order of admin's changelist filters in the querystring relied on
dict ordering.

Backport of 4d996b8e from master

Thanks Keryn Knight.

Backport of 246face2 from master

Backport of 981b864f from master

Thanks to trac username honyczek for the report. Refs #6903.

Backport of 4339e9a9 from master

Backport of d57ba04d from master

Backport of 029d77ea from master

Backport of 0fd51cf0 from master

Backport of a449e7fe from master

cb5dd99b from master.

Backport of 47509e3c from master

Backport of 69a4f383 from master

There may be more than 100 (default maxsize) commonly seen xx-yy values
on some sites. The additional memory consumption isn't significant.

Also added a comment explaining why this cache must have a maxsize.

Backport of f356b6ec from master.

Thanks lee at semel.net for the report.

Backport of f30e6590 from master

Thanks to gwahl@fusionbox.com for the report.

Backport of 21f208e6 from master

Code borrowed from django.contrib.admin.tests. Without this, the class can
throw an exception with something like "The browser appears to have exited
before we could connect. The output was: Error: no display specified"

Backport of e2ac0203 from master

Backport of 306deab2 from master

Thanks cjerdonek for the report.

Backport of a7797577 from master

The test throws an error which Python 3.4 doesn't seem to catch as an
expectedFailure.

refs 7476d96f

Backport of c170c376 from master

Backport of c19bbefc from master

Backport of b077ba7a from master

Thanks to @loic for the help and @timgraham for the review.

refs #12030.

Backport of b9e50e47 from master

All signals should now be registered in AppConfig.ready().

Thanks un33k for the report.

Backport of 5233b366 from master

Backport of 45ef4baf from master

This commit reverts 69d4b1c3 and tackle the issue from a different angle.
Models remain present in the project state, but are now ignored by the
autodetector.

Backport of 42336c84 from master

Backport of 378359de from master

refs #12030.

Backport of ff874f36 from master

Thanks to @timgraham for the review.

Backport of 1506c71a from master