A way to show all my branches on github

have you tried to use

github.com/yourrepository/branches/yours

It works in my projects but I do not know if somebody have done that

I am not aware of a way to do this. While this is not definitive, my initial search of the help on github suggests that it's not currently possible. Based on this link: https://help.github.com/articles/searching-code/

Only the default branch is considered. In most cases, this will be the master branch.

Also, there's nothing about branches on the advanced search page, sad to say: https://help.github.com/articles/advanced-search/