This is a work in progress, but here is a partial:

The first time I see a break in the prior expected behavior was on 11/19/2017 (c61ee94959ba96b2a327df0684593f7e569e30be) when portions of Emacs 25 were merged with the master branch and `emacs.c` was modified.  Here is a partial reversal of the code that broke the ability to avoid a stack overflow by setting `ulimit -S -s unlimited`.  The patch applies to the above-mentioned head -- i.e., the patch will apply following a hard reset.

I have not yet been able to follow the subsequent breaks to avoid a stack overflow with the current master branch.