Bugfixes:
- Release the savepoints in copy_remote_data_to_repo (Julien Rouhaud, thanks to Thomas Reiss for the report)
- Restore compatibility with standard_conforming_strings = off (Julien Rouhaud, thanks to github user rafaelorafaelo for the report)
- Properly detect and report missing extensions (Julien Rouhaud, thanks to github users jw1u1 and rafaelorafaelo who both reported the problem)