Commit Predecessor in RCA Tree missing

[amtsvch]

Now only a current commit (its full SHA) is shown in the RCA-generated call tree files.
It'd be helpful to have also its predecessor shown. Especially useful, when the direct predecessor was not runnable for some reason.

It would speed up manual analysis of testcases.

[DaGeRe]

Thanks for the issue, this should work starting with 4024ced, does this work for you?

[amtsvch]

Yes, thanks!