Merge branch 'ps/guess-repo-name-at-root'

Merge branch 'ps/guess-repo-name-at-root'

"git clone $URL", when cloning from a site whose sole purpose is to
host a single repository (hence, no path after <scheme>://<site>/),
tried to use the site name as the new repository name, but did not
remove username or password when <site> part was of the form
<user>@<pass>:<host>.  The code is taught to redact these.

* ps/guess-repo-name-at-root:
  clone: abort if no dir name could be guessed
  clone: do not use port number as dir name
  clone: do not include authentication data in guessed dir