Also make sure that we're actually running the test from within the right
cwd, like we do when we're building.  This seems necessary to avoid
an error when running offline.

Amusingly, it appears that we had this bug before: we just weren't
noticing it, because of bug 26258.

Shouldn't send RELAY_COMMAND_DATA cell with 0 stream id.

"ours" to avoid version bump.

"ours" merge to avoid version bump.

Remove the "documentation" section, since a comment-only change
doesn't usually get a changelog entry.