Command to retrieve path to .nimble file
/cc @dom96 
all other packages foo I installed after `nimble develop` behaved like:
`nimble path foo` returns /Users/timothee/git_clone/nim/foo
but not nimble:
`nimble path nimble` returns /Users/timothee/git_clone/nim/nimble/src instead of /Users/timothee/git_clone/nim/nimble