loaddata can load fixture data multiple times, if specified with absolute pathname

[btoll <btoll@…>]

Attached patch includes a regression test that demonstrates issue, along with a proposed fix (for review).

The situation can arise if a project has a test fixture that is maintained outside of the project structure. An attempt to load the fixture with an absolute path, e.g.

python manage.py loaddata /path/to/fixture

will work, but consumes more time and memory than necessary, since the fixture data will be loaded once for every fixture directory in a project (in either an installed application or FIXTURE_DIRS).

This effect can be observed in the count of objects and fixtures that are reported by the loaddata command. Setting '--verbosity=2' makes it more apparent.

[btoll <btoll@…>]

Regression test and proposed fix

[Russell Keith-Magee]

(In [7145]) Fixed #6436 -- Added check for absolute paths in fixture loading. Fixtures specified as an absolute path were being loaded multiple times. Thanks to btoll@… for the report, fix, and catch of a duplicate ticket.