str/bytes mismatch in ManifestFilesMixin causes failure on Python 3

[David Evans]

The issue is that load_manifest returns bytes rather than a string which then gets fed into json.loads inside read_manifest resulting in:

TypeError: can't use a string pattern on a bytes-like object

read_manifest doesn't get exercised in the test suite, hence the issue not being spotted.

I'll try to submit a patch soon, but just registering the issue first.

[David Evans]

Pull request here: ​https://github.com/django/django/pull/2463

[Tim Graham <timograham@…>]

In 86dcac463437dce06ddcade10fa3f308436ba608:

Fixed #22315 -- str/bytes mismatch in staticfiles

Previously, ManifestFilesMixin.read_manifest failed in Python 3
because json.loads accepts str not bytes.

[Tim Graham <timograham@…>]

In ddcbde41eec12f7a84b00635cdbf1c93d4e4d297:

[1.7.x] Fixed #22315 -- str/bytes mismatch in staticfiles

Previously, ManifestFilesMixin.read_manifest failed in Python 3
because json.loads accepts str not bytes.

Backport of 86dcac4634 from master