Revert "cleaning failures for selecting gemsets"

This reverts commit a28b0a426a51ec18f0eeccfdb60fc7da1e45d438.
Revert "do not parse ruby name when it is already installed, fix #2503"

This reverts commit cb39d135b81a050a0a7bd117cbdfa80f1a9ecee0.
do not parse ruby name when it is already installed, fix #2503
cleaning failures for selecting gemsets