Historically, Django Evolution would set up its baselines (Version and

Evolution entries) in response to a syncdb (and, in recent

development, migrate). Along with this, it would output messages saying

which apps needed to be evolved, and which baselines were being

installed. This was designed in part to help provide instructions, since

evolve had to be run alongside syncdb, and the order mattered.
With the introduction of the Evolver, the entire process is designed

to be done in one command (evolve --execute). There's no longer a need

to output any hints or to diff any signatures. The generation of

baselines can also be streamlined, and database writes optimized,

massively reducing unit test runs.
Further, we no longer need or want to do this every time we react to

this signal. If an Evolver.evolve() operation is running, then

baselines are already being managed, and there's no point in doing

anything at all. Instead, we only need to do this when we get these

signals outside of the Evolver (such as during unit tests or database

flushes).

Unit tests pass on all supported versions of Django.