Prob distr stochastic tests fail CI (innocuous?)
The stochastic tests are failing the CI as we expected. This is a ticket to collect such failures, to eventually see if they are really innocuous or there is some underlying bug. At this point I have two such failures collected both for the same stochastic test (log-logistic):
```
slow/prob_distr/stochastic_log_logistic: [forking] fail log logistic sampler
another stochastic test fail
Seed: D3CF5E3899188E3357D47061E936FF96
```
```
slow/prob_distr/stochastic_log_logistic: [forking] fail log logistic sampler
FAIL ../src/test/test_prob_distr.c:1390: assert(ok)
NOTE: This is a stochastic test, and we expect it to fail from
time to time, with some low probability. If you see it fail more
than one trial in 100, though, please tell us.
Seed: 883CEA3493C96F8D59EE7A6554EB594E
```
issue