* Handle push rejections and push out-of-date in branch creation and
file upload.
* Remove the duplicated sanitize from services/pull/merge
* Move the errors Err(Merge)PushOutOfDate and ErrPushRejected to
modules/git
* Handle errors better in the upload file dialogs
Fix#10460
Signed-off-by: Andrew Thornton <art27@cantab.net>
Co-authored-by: guillep2k <18600385+guillep2k@users.noreply.github.com>