scripts/debcheckout.pl: handle DEBEMAIL including DEBFULLNAME in name <mail> format

What is the canonical definition of how DEBEMAIL should look like? I was setting up a new system and made the mistake of using the man page of dch to learn that DEBEMAIL can be of the format name <mail> and if it is, DEBFULLNAME does not need to be set. The problem is, that debcheckout does not understand this format and in my case it creates a ~/.git/config containing:

[user]
email = Johannes Schauer Marin Rodrigues <josch@debian.org>

This leads to commits that look like this:

Author: Johannes Schauer Marin Rodrigues <Johannes Schauer Marin Rodrigues josch@debian.org>

Unfortunately, I noticed this too late and now several Debian git repositories contain git commits by me with a completely garbage email address including the packaging repositories of zxing-cpp, fakechroot, clapper, mmdebstrap as well as devscript itself! See the Author field of the commits in !320 (merged)

Lets make sure I'm the last person who has a garbage email address enshrined for all eternity in several git repositories that i cannot change the history of without breaking other people's clones...

Please merge this or help me make this change mergable.

Thanks!