copyright: update to 2019 Differential Revision: https://phab.mercurial-scm.org/D5779

revlog: make sure we never use sparserevlog without general delta (issue6056) We are getting user report where the delta code tries to use `sparse-revlog` logic on repository where `generaldelta` is disabled. This can't work so we ensure the two booleans have a consistent value. Creating this kind of repository is not expected to be possible the current bug report point at a clonebundle related bug that is still to be properly isolated (Yuya Nishihara seems to a have done it). Corrupting a repository to reproduce the issue is possible. A test using this method is included in this fix.

sparserevlog: document the config option This was overlooked when this graduated from experimental.

rust-cpython: raising error.WdirUnsupported The Graph implementation of hg-cpython returns the appropriate error upon encounter with the working directory special revision number, and this gives us in particular a code path to test from test-rust-ancestors.py In the current implementation, the exception is actually raised from the iterator instantiation; we are nonetheless consuming the iterator in the test with `list()` in order not to depend on implementation details.

rust: error for WdirUnsupported with cpython conversion as exception This introduces WorkingDirectoryUnsupported as an enum variant of GraphError in the core and converts it to the expected `mercurial.error.WdirUnsupported`.

rust: working directory revision number constant This introduces the constant, but does not use it anywhere yet.