Support empty fragmenets like a{,b}c
Support empty fragmenets like a{,b}c

zetamatta/nyagos,tyochiai/nyagos,kissthink/nyagos,kissthink/nyagos,kissthink/nyagos,hattya/nyagos,tsuyoshicho/nyagos,hattya/nyagos,nocd5/nyagos,hattya/nyagos