Yes, we've seen the exact same error.
I guess the reason is that Galaxy tries to use a slightly outdated version of amqp.
amqp 1.4.7 fixes the El Capitan incompatibility and should be used instead.
To fix this immediately for your current installation, this should work (though I haven't tried it yet):
in the file /Users/jaeilhan/Downloads/galaxy-dev/eggs/amqp-1.4.6-py2.7.egg/amqp/five.py replace the line:
libSystem = ctypes.CDLL('libSystem.dylib')
libSystem = ctypes.CDLL(find_library('libSystem.dylib'))
We are aware of this and are working on the fix. It is possibly caused by Kombu and amqp having trouble on _some_ el capitans.
"Fixed libSystem import error on some OS X 10.11 (El Capitan) installations."
Thanks for reporting