Taskcluster-taskgraph

Fixed

- Set HGPLAIN environment variable for Mercurial commands in util/vcs.py

Fixed

- Fix exception in default parameters when no git remote named "origin"

Fixed

- Used repository root as default in `get_repository` rather than cwd
- Retry vcs commands in run-task if they failed

Fixed

- An import error with Python 3.10

Fixed

- Search ancestor directories when instantiating repo in `get_repository`

Added

- Support specifying defaults to `extend_parameters_schema` utility
- Added `beetmover` payload builder to `task.py` transforms

Fixed

- Fixed logging error when using `taskgraph --diff`
- Various fixes to `Repository` utility class in `vcs.py`