The current setup fails with a "cannot read tree" error.
Also added flags to parallelise each fetch, which is relevant when submodules
are involved. (So, pretty much just starter-kit, haha.)
It would be nice to also parallelise the various fetches, but that would hit
the same remote multiple times, and could lead to rate-limiting...
libbet now uses `py -3` if the `py` binary exists, instead of if
`COMSPEC` is defined. So we don't need to `unset COMSPEC`, we just
need to avoid Windows' `py` launcher from being in Cygwin's `PATH`.
It turns out that `C:\cygwin\bin\env.exe CYGWIN_NOWINPATH=1 ...`
was not effectively preventing Windows' `PATH` from being inherited
by Cygwin's `PATH`, because to take effect it needs to run Cygwin's
`/etc/profile` script. The simple way to do that is using a login
shell. So we don't need the `PREFIX`/`--prefix` from the previous
commit after all.
- Use CTest labels to filter tests ("internal"/"external", "free"/"nonfree",
and individual tool+project names) instead of defining `TESTS_RUN_NONFREE`
- Allow each external test to run independently in CTest
- Remove the unused no-op `fetch-test-deps.sh --only-internal` option