I noticed that on the most recent Ubuntu 15.04, many lib*-dev packages have their dependencies set up according to the following pattern:
Package: libstdc++-4.9-dev
[...]
Breaks: libstdc++-4.9-dev (!= 4.9.2-10ubuntu13)
Replaces: libstdc++-4.9-dev (< 4.9.2-10ubuntu13)
What would be the reason to declare that libstdc++-4.9-dev breaks all other versions of the package? Isn't it impossible to install more than one version of the same package anyways? And couldn't the package overwrite its own files even without the replaces line?
