Package: main
Version: 1
Architecture: amd64
Depends: d, b, c
Description:
 forces to install a real package a(=1), and two packages providing a(=1) 

Package: a
Version: 2
Architecture: amd64
Provides: d

Package: b
Version: 1
Architecture: amd64
Provides: a (=1)

Package: c
Version: 42
Architecture: amd64
Provides: a (=1)
