One shortcoming of the CPAN clients that currently exist is that they have no way of specifying conflicting downstream dependencies of modules. This module attempts to work around this issue by allowing you to specify conflicting versions of modules separately, and deal with them after the module is done installing.
For instance, say you have a module 'Foo', and some other module 'Bar' uses 'Foo'. If 'Foo' were to change its API in a non-backwards-compatible way, this would cause 'Bar' to break until it is updated to use the new API. 'Foo' can't just depend on the fixed version of 'Bar', because this will cause a circular dependency (because 'Bar' is already depending on 'Foo'), and this doesn't express intent properly anyway - 'Foo' doesn't use 'Bar' at all. The ideal solution would be for there to be a way to specify conflicting versions of modules in a way that would let CPAN clients update conflicting modules automatically after an existing module is upgraded, but until that happens, this module will allow users to do this manually.