Faster room joins: avoid blocking when pulling events with missing prevs (#13355)

Avoid blocking on full state in `_resolve_state_at_missing_prevs` and
return a new flag indicating whether the resolved state is partial.
Thread that flag around so that it makes it into the event context.

Co-authored-by: Richard van der Hoff <1389908+richvdh@users.noreply.github.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/changelog.d/13355.misc b/changelog.d/13355.misc
new file mode 100644
index 0000000000..7715075885
--- /dev/null
+++ b/changelog.d/13355.misc
@@ -0,0 +1 @@
+Faster room joins: avoid blocking when pulling events with partially missing prev events.