From 946ec98b6bd74175f62dbb257f1b8301ad722727 Mon Sep 17 00:00:00 2001
From: Patrick Cloke <patrickc@matrix.org>
Date: Wed, 26 Feb 2020 10:30:04 -0500
Subject: [PATCH 1/4] Properly convert a coroutine into a Deferred for
 federation_base.

---
 synapse/federation/federation_base.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/synapse/federation/federation_base.py b/synapse/federation/federation_base.py
index eea64c1c9f84..da4fe03b5e9e 100644
--- a/synapse/federation/federation_base.py
+++ b/synapse/federation/federation_base.py
@@ -96,13 +96,13 @@ def handle_check_result(pdu, deferred):
 
             if not res and pdu.origin != origin:
                 try:
-                    res = yield self.get_pdu(
+                    res = yield defer.ensureDeferred(self.get_pdu(
                         destinations=[pdu.origin],
                         event_id=pdu.event_id,
                         room_version=room_version,
                         outlier=outlier,
                         timeout=10000,
-                    )
+                    ))
                 except SynapseError:
                     pass
 

From d64095b1d6f40c2a162e0e527d184dd1321f030b Mon Sep 17 00:00:00 2001
From: Patrick Cloke <patrickc@matrix.org>
Date: Wed, 26 Feb 2020 10:35:47 -0500
Subject: [PATCH 2/4] Add changelog file.

---
 changelog.d/6996.bugfix | 1 +
 1 file changed, 1 insertion(+)
 create mode 100644 changelog.d/6996.bugfix

diff --git a/changelog.d/6996.bugfix b/changelog.d/6996.bugfix
new file mode 100644
index 000000000000..c97d96168c41
--- /dev/null
+++ b/changelog.d/6996.bugfix
@@ -0,0 +1 @@
+Properly handle the result of FederationClient.get_pdu as a coroutine.

From 126f3bd2595a697aa3e42239bb4c9691fbb7647a Mon Sep 17 00:00:00 2001
From: Patrick Cloke <patrickc@matrix.org>
Date: Wed, 26 Feb 2020 10:36:40 -0500
Subject: [PATCH 3/4] Run black.

---
 synapse/federation/federation_base.py | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/synapse/federation/federation_base.py b/synapse/federation/federation_base.py
index da4fe03b5e9e..9fff65716ae2 100644
--- a/synapse/federation/federation_base.py
+++ b/synapse/federation/federation_base.py
@@ -96,13 +96,15 @@ def handle_check_result(pdu, deferred):
 
             if not res and pdu.origin != origin:
                 try:
-                    res = yield defer.ensureDeferred(self.get_pdu(
-                        destinations=[pdu.origin],
-                        event_id=pdu.event_id,
-                        room_version=room_version,
-                        outlier=outlier,
-                        timeout=10000,
-                    ))
+                    res = yield defer.ensureDeferred(
+                        self.get_pdu(
+                            destinations=[pdu.origin],
+                            event_id=pdu.event_id,
+                            room_version=room_version,
+                            outlier=outlier,
+                            timeout=10000,
+                        )
+                    )
                 except SynapseError:
                     pass
 

From a0e61479f8c1cfb31f6adf58c5ab28d15c0b0be2 Mon Sep 17 00:00:00 2001
From: Patrick Cloke <patrickc@matrix.org>
Date: Wed, 26 Feb 2020 11:07:28 -0500
Subject: [PATCH 4/4] Update the changelog entry.

---
 changelog.d/6996.bugfix | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/changelog.d/6996.bugfix b/changelog.d/6996.bugfix
index c97d96168c41..765d376c7c7c 100644
--- a/changelog.d/6996.bugfix
+++ b/changelog.d/6996.bugfix
@@ -1 +1 @@
-Properly handle the result of FederationClient.get_pdu as a coroutine.
+Fix bug which caused an error when joining a room, with `'coroutine' object has no attribute 'event_id'`.