We discussed that over IRC, but in a nutshell:
- editor shared objects have static TLS (why exactly this happens despite us passing -ftls-model=local-dynamic is yet unknown)
- glibc has a total limit of 14 static TLS slots (bumped up to 32 in Ubuntu 15.04 and Fedora): Carlos O'Donell - Fixing the distribution problems with TLS and DTV_SURPLUS slots.
- on Ubuntu 14.04 and up our shared objects + whatever system shared objects happen to use static TLS as well together still use fewer slots than the system limit (14 or 32).
- on Arch apparently this is not the case.
Proper fix is making editor shared objects not to use static TLS. Short term fix would be patching Arch glibc to increase DTV_SURPLUS.