add a first cut at the horrible mass resigning process

Signed-off-by: Kevin Fenzi <kevin@scrye.com>

modules/release_guide/pages/sop_mass_branching.adoc

@@ -10,6 +10,51 @@ bugfix and polish mode.
 
 You will find below the list of steps to follow to branch a new Fedora release.
 
+== Mass resigning
+
+When we branch off of rawhide, the branched release packages are already signed by
+the F{release} key, but we need to resign everything in rawhide for the new F+1 key.
+ie, When we branch f39 off rawhide, all it's packages are already signed by the f39
+key, but we need to resign everything with the f40 key for rawhide.
+
+* Add a new config for the new key to robosignatory. Something like:
+
+```
+            [[consumer_config.koji_instances.primary.tags]]
+            from = "f39"
+            to = "f39"
+            key = "{{ (env == 'production')|ternary('fedora-40', 'testkey') }}"
+            keyid = "{{ (env == 'production')|ternary('a15B79cc', 'd300e724') }}"
+            {% if env == "production" %}
+            file_signing_key = "fedora-40-ima"
+            {% endif %}
+```
+This allows robosignatory to sign packages in the f39 tag with the f40 key.
+* git clone https://pagure.io/releng
+* confirm the new key fingerprint is in scripts/sigulsign_unsigned.py
+* run sigulsign_unsigned.py to gather list of packages to sign:
+```
+./sigulsign_unsigned.py --just-list --tag f39 fedora-40 | grep src | sed -e 's|.src||' > unsigned-packages
+```
+You should get a list of all the source packages by name.
+* copy unsigned-packages list to autosign01
+* on autosign01 run in a tmux session:
+```
+sudo -su robosignatory
+passphrase=$(systemd-ask-password "Please enter passphrase for 'autosign' key: ")
+(enter the autosign passphrase)
+keyctl add user "sigul:autosign" "${passphrase}" @s
+for i in `cat unsigned-packages`
+do
+  echo $i;
+  robosignatory sign-tag primary $i f39;
+  sleep 1;
+done
+```
+This will iterate over all packages and sign them with the new f40 key.
+Once complete, re-run the ./sigulsign_unsigned.py command to confirm all are signed.
+On branching day, remove the robosignatory config for this resigning.
+
 == Send announcement
 
 One day before the mass branching, we send out announcemt because during mass branching,