Nextcloud/docker

Hi, I am new in contributing to Nextcloud. I want to make a contribution but I have 2 problemes:
1: the DCO
I want to Signed-off-by: pierre <pierre.m@nikolov.fr> but it fails each time.
It works with the following Signed-off-by: pierre <pierre@pierre.p.nikolov.fr>
How can I solve this issue?

2: continuous-integration/travis-ci/pr
I get the following error:
The command "bash -c "[[ $hash_before = $(git add -A && git write-tree) ]]"" exited with 1
How can i fix the error?

Here is the contribution https://github.com/nextcloud/docker/pull/683
Thanks for you help

I answered both of your questions on GitHub: