Since today's update to the beta channel that Steam just hangs one core at 100% when starting and it never opens.

This is what I got running from a console:
$ steam
Running Steam on arch rolling 64-bit
STEAM_RUNTIME is enabled automatically
Installing breakpad exception handler for appid(steam)/version(1379035603_client)
Installing breakpad exception handler for appid(steam)/version(1379035603_client)
Installing breakpad exception handler for appid(steam)/version(1379035603_client)
Installing breakpad exception handler for appid(steam)/version(1379035603_client)
unlinked 0 orphaned pipes
removing stale semaphore last operated on by process 3044 with name 0eBlobRegistryMutex_4EAF69863D7F5334DF6CFCD94AE60E53
removing stale semaphore last operated on by process 3044 with name 0eBlobRegistrySignal_4EAF69863D7F5334DF6CFCD94AE60E53
removing stale semaphore last operated on by process 3044 with name 0emSteamEngineInstance
removing stale semaphore last operated on by process 3044 with name 0eSteamEngineLock
Installing breakpad exception handler for appid(steam)/version(1379035603_client)
Fontconfig error: "/etc/fonts/conf.d/10-scale-bitmap-fonts.conf", line 70: non-double matrix element
Fontconfig error: "/etc/fonts/conf.d/10-scale-bitmap-fonts.conf", line 70: non-double matrix element
Fontconfig warning: "/etc/fonts/conf.d/10-scale-bitmap-fonts.conf", line 78: saw unknown, expected number
[0913/123742:WARNING:proxy_service.cc(958)] PAC support disabled because there is no system implementation

After this, nothing shows up and a CPU core is at 100% usage.

Also tried deleting ~/.steam and ~/.local/share/Steam and reinstalling. Steam works fine as long as I don't join Beta. As soon as it updates to the Beta version, same thing happens again.