Yes, it is in debian/control:
Package: python-matplotlib [...] Provides: ${python:Provides} Conflicts: python2.4-matplotlib Replaces: python2.4-matplotlib [...]
Yes, it is in debian/control:
Package: python-matplotlib 4-matplotlib 4-matplotlib
[...]
Provides: ${python:Provides}
Conflicts: python2.
Replaces: python2.
[...]