This was a vestige from when we used to need the unittest2 library for pre-2.7
compatibility. Now that we require Python 2.7, we aren't using that library
and this indirection wasn't doing any good.
This reverts commit 9c41c39913.
That commit used byte strings for the `if __name__ == '__main__'` pattern,
which was necessary when we were doing unicode_literals. But it is wrong on
Python 3, and now that we're liberated from unicode_literals, we need to go
back to native strings for this comparison.
Include import of __future__ features division, absolute_imports and
print_function everywhere. Don't add unicode_literals yet for it is
harder to convert.
Goal is smoothing the transition to python 3.
Instead of recording only the most recently imported path and assuming
that all previous path have also been imported, we record all imported
paths and skip recorded paths when resuming the import.
This fixes an issue where parallelism would screw up the import order
and reimport some files. It also allows us to record singleton items.
We can apply the same strategy can be applied for incremental imports.
The goal of this class is to eliminate all checks for `task.is_album`. This is
already accomplished for the methods. Next, we want to tackle the plugin
stages.
