method: clarify the fail message
method: clarify the fail message

Fixes #1431 (Error message typo. ("gem-install"))

tdg5/pry,caporta/pry,josue804/debunker,jasonm23/pry,jasnow/pry,shockone/pry,printercu/pry,josue804/debunker,pvdb/pry,scalixte-mdsol/pry,raeno/pry,85x14/pry,raeno/pry,tdg5/pry,printercu/pry,jasnow/pry,jasonm23/pry,tdg5/pry,ngpestelos/pry,scalixte-mdsol/pry,caporta/pry,raeno/pry,ooohiroyukiooo/pry,caporta/pry,85x14/pry,scalixte-mdsol/pry,bronzdoc/pry,geoffreylitt/pry,ooohiroyukiooo/pry,jasnow/pry,pvdb/pry,geoffreylitt/pry,ngpestelos/pry,bronzdoc/pry,gfvcastro/pry,shockone/pry,icebreaker/pry,nju520/pry,shockone/pry,nju520/pry,ooohiroyukiooo/pry,gfvcastro/pry,icebreaker/pry,nju520/pry,jasonm23/pry,85x14/pry