note problems we had on the ganeti upgrades

howto/upgrades/bullseye.md

@@ -336,8 +336,12 @@ after:
     
         cumin 'C:roles::ganeti::chi' "apt install -y ganeti/buster-backports"
 
-    There was a change on the `/etc/default/ganeti` file. The diff was
-    checked with:
+    but this actually **FAILED** in recent attempts, with:
+    
+        E: The value 'buster-backports' is invalid for APT::Default-Release as such a release is not available in the sources
+    
+    There may be a change on the `/etc/default/ganeti` file. The diff
+    was checked with:
 
         cumin 'C:roles::ganeti::chi' 'diff -u /etc/default/ganeti.dpkg-dist /etc/default/ganeti'
 
@@ -354,6 +358,13 @@ after:
     
         gnt-cluster renew-crypto --new-cluster-certificate
 
+    This step *may* fail to start daemons on the other nodes,
+    something about the pid file not being owned by `root`. We haven't
+    figured out exactly what happens there but the current theory is
+    that something may be starting the Ganeti daemons behind that
+    process' back, which confuses the startup script. The workaround
+    is to run the exact same command again.
+
  4. on the master, verify the cluster
 
         gnt-cluster verify