Description of Problem:

When Evo is set to a language that has multiple letters representing a
single letter, such as Welsh, where ch, ph, ll and others are considered a
single letter, contacts doesn't work as expected. For example, picking "ph"
from the list on the right-hand side displays all surnames starting with
either p or h, not all surnames that start with ph.

Steps to reproduce the problem:
1. Switch to a locale such as cy (and have the .mo files installed -
available from http://muse.19inch.net/~daf/gnome-cy/cy.mo.tar.gz)
2. Open Evo and switch to the Contacts view (Cysylltion in Welsh)
3. Ensure you have contacts whose surnames start with p and h
4. Select "ph" from the list of letters on the right-hand side

Actual Results:
Evo displays contacts whose surnames start with either p or h

Expected Results:
Evo should display contacts whose surnames start with ph

How often does this happen? 
Always

Additional Information:
A screenshot is available at http://big.tgb.org.uk/~tgb/evo.png showing
this behaviour.

This behaviour happens for all double-letter letters, not just ph :)