How to correctly handle different lib trunks

["Salvatore Ansani" <ml@ansani.it>]

Hi mentors,
not a technical question this time :)

I want to understand how to correctly handle various libs versions.

Let me start with an example.

Suppose a package, yet in debian unstable repo, currently depend on kdelibs5 
(4.0.2 for example).
If I upgrade my kde to 4.0.66+svn... I break all my dependencies and my old 
package need to be removed.

If I recompile sources on my new environment all is ok and package work 
correctly.

Now the question... How I can handle this new build ??? Package is obviously 
experimental but, if I change version with package_oldversion_SVNBLABLABLA, 
I break some policy ???

Regards,
Salvatore