nvm run: use common code path for "ensure version installed"
nvm run: use common code path for "ensure version installed"

Better than cb033adc6f8fa0987ab4268b6298b7161c972c52
slariviere/nvm,Theodeus/nvm,Kuzirashi/nvm,jaawerth/nvm,edwmurph/nvm,creationix/nvm,jaawerth/nvm,thomasf/nvm,tlevine/nvm,evocateur/nvm,PeterDaveHelloKitchen/nvm,lukechilds/nvm,bevacqua/nvm,lukechilds/nvm,ljharb/nvm,creationix/nvm,PeterDaveHelloKitchen/nvm,dfackler/nvm,fnogatz/swivm,thomasf/nvm,Theodeus/nvm,Kuzirashi/nvm,dfackler/nvm,tlevine/nvm,evocateur/nvm,slariviere/nvm,bevacqua/nvm,ljharb/nvm,PeterDaveHello/nvm,PeterDaveHello/nvm,edwmurph/nvm