`nvm_change_path` prepends the new version
(instead of replacing the existing nvm path)
when a system bin dir precedes an nvm path,
to handle macOS `path_helper` reordering the `PATH` of nested sessions
(#1652). However, the check matched a system dir followed by *any* nvm path.
Once a stale nvm path sits after the system dirs
(e.g. inherited by a nested shell, tmux, or an editor's terminal),
the check stays true forever,
so every `nvm use` prepends yet another entry and the previously used version is never removed from the `PATH`.
Only consider the first nvm path:
if it is not preceded by a system bin dir,
replace it in place as usual.
Fixes#3561
maliv2
bfabdbc278