Advice on advice needed

[Marcin Borkowski <mbork@wmi.amu.edu.pl>]

Hello,

and sorry for the lame pun in the topic.

There is a function in Emacs which really should be wrapped in
`save-excursion' (it's `message-insert-signature').  I advised it, so
that I can repeatedly press C-c C-w to cycle between a few signatures.
However, it puts the point at the end of the buffer.

Is there a way to wrap it in `save-excursion' using advice, or is
writing a wrapper function the only way to do it?  (I guess the latter,
but maybe I'm wrong?)  I'm on Emacs 25.0.50.1, so I have the “new
advice” system on board.

TIA,

-- 
Marcin Borkowski
http://octd.wmi.amu.edu.pl/en/Marcin_Borkowski
Faculty of Mathematics and Computer Science
Adam Mickiewicz University