We have checks to try and catch the case where Synapse is being run from
a source directory, but the compiled Rust code is out-of-date. This
commonly happens when Synapse is updated without running `poetry
install` (or equivalent).
These checks did not correctly handle `.egg-info` installs, and so were
not run.
Currently, the `.egg-info` directory is created automatically by poetry
(due to using setuptools to build Rust).
d143276bda