When using an alternative backend (such as hypothesis-crosshair),
Hypothesis no longer emits a "test_case" observation for an iteration
that the backend aborts via "BackendCannotProceed" before the test
body runs. Previously such an iteration -- for example when the
crosshair backend has exhausted its search paths -- could surface as a
spurious, draw-less "passed" observation with an empty representation,
even though the engine already discards the iteration entirely.
The canonical version of these notes (with links) is on readthedocs.