Currently testing a home build of shamu (Nexus 6) on my phone. So far, no errors found except I can’t install a TWRP so I keep getting a message that it’s out of date. Testing.
I ran the build on Xubuntu 18.04 and didn’t get that error.
First, did you run the exact commands from ( https://gitlab.e.foundation/e/wiki/en/wikis/build ) except replacing “kiwi” with “shamu”? I see “herolte” as the device on your screenshot so I’m figuring this might be part of the problem. If you are building for “herolte”, I’m not going to be much help since I built for shamu.
Second, did you follow the Docker install instructions exactly?