more tinkering with whence

[Ray Andrews <rayandrews@xxxxxxxxxxx>]

All good:
    $ whence -mav global
    global is a shell function
    global is /usr/local/bin/global

Rename the file:
    $ mv /usr/local/bin/global /usr/local/bin/gglobal

It now says 'not found', which is true, but ...
    $ whence -mav global
    global is a shell function
    global not found

Restart:
    $ zsh

... now it doesn't bother reporting that it's 'not found':
    $ whence -mav global
    global is a shell function

Rename the file back to 'global', and ...
    $ mv /usr/local/bin/gglobal /usr/local/bin/global

... the file isn't found at all:
    $ whence -mav global
    global is a shell function

Must restart to find it:
    $ zsh

... and there is is again:
    $ whence -mav global
    global is a shell function
    global is /usr/local/bin/global


Is there some way to update or inform whence that a new item
exists on the path, without restarting the shell? Is this
something involving the hash table?