Fixes #2539 by checking if extension was specifically supplied as an option.
Fixes #2539 by checking if extension was specifically supplied as an option.

anitagraham/refinerycms,KingLemuel/refinerycms,mabras/refinerycms,refinery/refinerycms,simi/refinerycms,Eric-Guo/refinerycms,bricesanchez/refinerycms,chrise86/refinerycms,sideci-sample/sideci-sample-refinerycms,chrise86/refinerycms,hoopla-software/refinerycms,LytayTOUCH/refinerycms,LytayTOUCH/refinerycms,aguzubiaga/refinerycms,simi/refinerycms,mkaplan9/refinerycms,stefanspicer/refinerycms,LytayTOUCH/refinerycms,Retimont/refinerycms,anitagraham/refinerycms,johanb/refinerycms,simi/refinerycms,Retimont/refinerycms,gwagener/refinerycms,bricesanchez/refinerycms,trevornez/refinerycms,gwagener/refinerycms,anitagraham/refinerycms,Retimont/refinerycms,mabras/refinerycms,Eric-Guo/refinerycms,sideci-sample/sideci-sample-refinerycms,johanb/refinerycms,mkaplan9/refinerycms,trevornez/refinerycms,trevornez/refinerycms,KingLemuel/refinerycms,johanb/refinerycms,mabras/refinerycms,mlinfoot/refinerycms,hoopla-software/refinerycms,hoopla-software/refinerycms,stefanspicer/refinerycms,simi/refinerycms,refinery/refinerycms,kappiah/refinerycms,kappiah/refinerycms,Eric-Guo/refinerycms,KingLemuel/refinerycms,aguzubiaga/refinerycms,stefanspicer/refinerycms,mlinfoot/refinerycms,gwagener/refinerycms,mkaplan9/refinerycms,mlinfoot/refinerycms,kappiah/refinerycms,chrise86/refinerycms,aguzubiaga/refinerycms,refinery/refinerycms