With the current ROOT master and v626 branch, the reading of some RooFit workspaces crashes consistently.

To reproduce this problem, one can try to read the WS-Comb-STXS_toy workspace from ATLAS:

# run this in the terminal first to not run out of stack space.
ulimit -S -s unlimited

auto f = TFile::Open("toyws/WS-Comb-STXS_toy.root");
auto w = (RooWorkspace*)f->Get("combWS");

This crash was introduced by these two commits, that were also backported to v626:

1. 79e101c
2. a5d205a

I list these two commits together, because ROOT doesn't compile at that first commit. So the second commit it the first one that compiles and crashes. The commit before these two, 819b4e3, is still OK.

If it would help to produce a simpler reproducer workspace, I'm glad to help out by trying to build one.