This should now depend on libmodman, which is up for review on #603514.
Thx for the update. Please request to be in ACL for libproxy once you will be sponsored.
There are some circle dependencies with the way libproxy is modularized.
So each time an ABI bump is involved, it might be needed to build libproxy one time only with core functionnalities, and a second time with all modules.
I realized this as soon as I tried building 0.4.4 in mock. I had to run out, but I will work on it later tonight.
0.4.4 is finally in rawhide.