Backport of be9d6453 from master

Backport of 8e86d9d3 from master

Backport of c21b832c from master

Backport of b99114f6 from master

Backport of 1a62f197 from master

Backport of 756a7272 from master

Backport of 3baebf52 from master

Backport of 783572ab from master

Backport of 64ed8cdc from master

Case expressions weren't copied deep enough (self.cases list was
reused resulting in an error).

Backport of 7b05d2fd from master

Backport of 9096e2b5 from master

The inner import was dropped during the reorganizing of the database
backends in commit 28308078.

Backport of 95058606 from master

Backport of 17b1f788 from master

Backport of 81f76517 from master

Thanks Preston Timmons for the report.

Backport of 1563b897 from master

Backport of b0bd1f0e from master

Backport of 3cb386b8 from master

Backport of 06aaed41 from master

Backport of 3c4fca27 from master

Backport of 2c3ce26b from master

Backport of 08c980d7 from master

Backport of 57202a11 from master

Updates for languages: Indonesian, Belarusian, Persian, and Dutch.

Backport of 29e90f3a from master

This is a regression caused by introducing rendered migration states in
1aa3e09c and the _meta refactoring in fb48eb05.

Thanks to Danilo Bargen for reporting the issue and Marten Kenbeek and
Tim Graham for triaging the bug and providing the initial test case.

Backport of 63f9b633 from master

Backport of cf34ee68 from master

Backport of 2b086229 from master

The test failed on RHEL6 systems running python 2.7 from a RedHat
Software Collection (SCL) because this test runs an external python
script with a stripped system environment. RedHat SCLs work by setting
a number of system environment variables when these are stripped out by
this test the python 2.7 interpreter is no longer able to function
properly because it can not find the system libraries needed.

Now we use use mock to modify the system environment directly.

Backport of 31e6c9c8 from master

Thanks to Andrew Ingram for the report.
Backport of 683ece0e from master.

Backport of 25b52d04 from master

Backport of 9c2d8cde from master

Backport of eaeea6f9 from master

Backport of d91321e8 from master

Backport of 0f2e82b9 from master

Thanks to Reto Aebersold for reporting the issue and Tim Graham and
Claude Paroz for the review.

Backport of faad6070 from master

I changed "appears" to "appear" and emphasized the word "not" to match
the rest of the document.

Backport of 0cf7477e from master

Backport of 9d6914da from master