We were passing the source branch name as the Branch value in the webhook data.
This patch will just delete this assignment. If in future it's needed let's add
it with a different name to not cause confusion.
Allow setting the destination branch/tag/ref so users can test the run
conditions based on the branch/tag/ref.
To simulate a pull request an user can define a ref that matches one of these
regular expressions: `refs/pull/(\d+)/head`, `refs/merge-requests/(\d+)/head`
Just a raw replace of "github.com/pkg/errors".
Next steps will improve errors (like remote errors, api errors, not exist errors
etc...) to leverage its functionalities
Simone Gotti