https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87281
--- Comment #9 from joseph at codesourcery dot com <joseph at codesourcery dot com> --- When using "build-many-glibcs <dir> checkout" to check out the source tree, you need to specify "gcc-vcs-mainline" after "checkout" to get GCC trunk sources checked out instead of the default of GCC 9 branch.
