That Launchpad bug is specific to the webapp; we need to look into what's going on with launchpad-buildd separately, so I'm adding a task to this bug for that. Please don't work around the problem in mplayer.
It's notable that s390x succeeded once the build-dependencies were finally satisfied. That suggests that this is in fact a problem with the sbuild or dpkg backports to earlier series.
That Launchpad bug is specific to the webapp; we need to look into what's going on with launchpad-buildd separately, so I'm adding a task to this bug for that. Please don't work around the problem in mplayer.
It's notable that s390x succeeded once the build-dependencies were finally satisfied. That suggests that this is in fact a problem with the sbuild or dpkg backports to earlier series.