Under bash's `set +h`, `hash -r` errors with "hash: hashing disabled",
which is then printed on every `nvm use`, including the one at shell startup.
Guarding on `$-` alone would be wrong:
`zsh` never puts `h` in `$-` - there `h` is `HIST_IGNORE_DUPS` -
and `dash` has no `h` flag at all,
so it would skip the call in 3 of the 4 shells the fast suite runs.
Gate on the shell instead, and skip only where the call fails:
bash under `set +h`, and `ksh93`, whose `hash` takes no `-r` and whose
usage error aborts `nvm use` before it can export `NVM_BIN`.
`ksh` is detected by probing rather than by version,
so `mksh` and `pdksh`, which do accept `-r`, keep getting the call.
The `${-#*h}` test is from #3910.
Refs #2065
Refs #3247
Jordan Harband
aeace4606f