We had issues that popped up with building of static media files. These

didn't prevent building static media, but mostly because we're lucky.
The first issue is that FORCE_BUILD_MEDIA wasn't being respected. We

were setting that using os.putenv() in build-media.py, but

settings.py was getting an empty string out when using os.getenv().
When calling os.putenv(), we don't actually modify the current

process, just subprocesses. The correct API to use is just os.environ,

which stores the variable in the local process's environment and wraps

os.putenv() for subprocesses.
This has been updated to just use os.environ in all cases.
Another is that we had conflicts when building files. Both

AppDirectoriesFinder and FileSystemFinder would find the exact same

static media files, and this would log complaints about duplicates.

Likely this isn't new behavior, but the logging is new.
The reason for the conflict is that we defined specific directories

containing static media files to process (for rb, djblets, and

lib), where the djblets version was also found in the djblets app

and rb and lib were found in the reviewboard app (both in

static/ directories).
We need reviewboard and djblets apps to be in INSTALLED_APPS,

since we reference templates and other state from there. Given that we

need these, and both contain static/ directories, we can get by with

just AppDirectoriesFinder. There's no need to keep FileSystemFinder

anymore, or maintain a list of STATICFILES_DIRS.

Tested a complete static files rebuild with both finders, without

FileSystemFinder, and without AppDirectoriesFinder. Backed up each

version and compared directory contents.
Removing FileSystemFinder had no effect on the contents of the directory,

but it did remove the errors.
Removing AppDirectoriesFinder caused a change in what files we collected,

ruling that out as an option.
Successfully built packages, ran the server without any static media issues,

and ran unit tests.