fL2 returns -infinity at beginning of run

[mathren]

As of commit cc3da9fec9c39c02bd85fac2bb0f56c200655a38 the function (in src/binary_disk.inc, copied from @pmocz MESA dev branch returns -infinity for fL2 when fed the numbers 20, 18, 0, 304, 0.1, 0.64, 0, 0.

To reproduce clone this particular commit, compile and run. Let both stars relax to their initial rotation (100 timestep of pseudo evolution per star), and see it segfault at the first step (when using r24.08.1). Add print statement just before each call to the function to see that inputs are all initialized and expected values.

Leaving this here as a note -- working around this enforcing fL2 = max(fL2, 1d-12) after calling that function.

[pmocz]

Great find! Looks like the original function I translated cannot handle the case when the input mass_transfer_rate=0, so I modified my function to return just 0 in this case, in the MESA PR: MESAHub/mesa#830

[mathren]

Yes, I confirm this fixed the issue (as of commit d52a2c7)! Thanks!