[tex-live] how to get tlmgr to list installed status for packages from a given (non-installed) collection

[jfbu]

Hi,

from
$ tlmgr info --list collection-mathscience

I get the list of packages included in the collection,
but not the information about installation status of them

trying 
$ tlmgr info --list --only-installed collection-mathscience

only tells me that the installation status
of collection-mathscience as a whole

I trust I have most of the packages (possibly all)
from collection-mathscience already installed.

Is there a way to get the info from tlmgr ? 

(or did the first
call above already return only the list of already
installed packages -- I don't expect so)

I can do a script scanning output of 
tlmgr info --list collection-mathscience
and then calling tlmgr again but maybe there
is a better way.


Jean-François