pub fn install_dirs(home: Option<&Path>) -> Vec<PathBuf>Expand description
Every fixed directory a channel installs into, whether or not it is on PATH.
Shared by devp doctor (which reports copies running a different version) and devp uninstall (which offers to sweep them up). They looked in different places before
this was one list, which meant doctor could report a stale copy that uninstall would
then fail to find.
Non-existent entries are included; callers filter. home is passed in so the list
can be tested without a home directory full of package managers.