mod=example.com/basic/v2
version=v2.1.2
base=v2.1.1-pre
proxyVersions=example.com/basic/v2@v2.1.1-pre
-- want --
example.com/basic/v2/a
----------------------
Incompatible changes:
- A2: removed

example.com/basic/v2/b
----------------------
Incompatible changes:
- package removed

Suggested version: v2.1.1