The key id format in the `regpg ls` output from gpg1 is like

    pub   4096R/15A1230B57A17C89 2017-11-02

and from gpg2 it is like

    pub   rsa4096/15A1230B57A17C89 2017-11-02 [SC]

Previously regpg would only strip off digits followed by one letter
then a slash. Now regpg strips off any alphanumeric+slash prefix.