This reverts commit 69bb270.

A crash seemed to occur in CI during garbage collection

julia:3364 terminated with signal 11 at PC=7f997aaec971 SP=7f9936ccb970.  Backtrace:
/opt/hostedtoolcache/julia/1.8.5/x64/bin/../lib/julia/libjulia-internal.so.1(ijl_gc_safepoint+0x11)[0x7f997aaec971]

This looks like a crash during garbage collection code (this would be consistent with the fact that it only shows up with allocation-heavy test, i.e. Turing).

So even though the finalizer checks first before calling free, maybe there is something flaky there.

#30 (comment)

Multi-threading issue seems not specific to Turing as crash occurred
for Blang in last commit.

…(0.5)

…rent project

Before this, we had crashed such as in
18ef655

Here is what was happening in these crash
1. parent process is using a system library
2. parent process' test first call local pigeons
3. that in turns called mpi_active() which internally used MPI.Init()
   to see if Comm_size > 1
4. that had the side effect of changing ENV
5. then, when calling pigeons MPI tests, these ENV variables were
   passed to ChildProcess, causing problems

The new approach avoids to call MPI.Init() frivolously