Probably does need an up to date NSS.
I tried building the RPM, for some reason my environment was rejecting the directive to use the git repository.
Last time I tried doing the proper build, I ran into problems which I now forget. It was a weird build method, build NSPR4, then use that build system to build NSS.
I believe the OS/2 code hasn't been removed from NSPR4 and NSS yet, but Bitwise patched it quite a bit. NSPR4 is sort of a universal libc.