Editing userids present on a key fails during passphrase entry when gnome-keyring's
gpg-agent is active.  If you disable gnome-keyring's gpg support then this issue goes
away (i.e thing work).  This problem also affects gpa and is a general problem due to
the fact that gnome-keyring has not kept pace with changes in gnugp (and
native gnupg-agent actually does all the 'addon' features of gnome-keyring except
the gnome-keyring core functionality and programs (or perhaps libgpgme) are written
for gnupg-agent not gnome-keyring)).