CI system may test against older SHA1 of modules when using a git mirror

When the test scripts invoke init-repository with one of the options enabling the usage of a git mirror, the refs mentioned in the tested module's sync.profile will be resolved from the mirror rather than the canonical repository. This can cause the usage of outdated versions of dependencies.

Note that init-repository will make the 'origin' remotes point towards the URL configured in qt5/.gitmodules, but it is not guaranteed that any fetch has been done from origin.