Use of dash instead of underscore for tryton package name

I’m wondering why tryton package names use underscore instead using dash as PEP8 suggests.

Exists any reason for that??

There are no particular reason except that the name is construct out of the module name which can not contain underscore.
If it does not break PyPI and others package manager, I do not see any reason to not improve the name.

It would be a little improvement, of course, but it’s all for symmetry, nothing more.

If you want to freeze a tryton installation for, by example, work with requirements.txt file you will get all tryton package names swapping underscore by dash.