Bug 1188815 - Update instructions on migrating from bzr to include switching server. r=LpSolit

docs/en/rst/installing/migrating-from-bzr.rst

@@ -8,4 +8,25 @@ Migrating from Bazaar
 .. |extstatusinfo| replace:: The command :command:`bzr status extensions/` should help you work out what you added, if anything.
 
 .. include:: migrating-from-1.inc.rst
+
+The old bzr.mozilla.org server has been decommissioned. This may not
+be a problem but, in some cases, running some of the commands below will
+make :command:`bzr` attempt to contact the server and time out. If and
+only if that happens to you, you will need to switch to the new server,
+as follows. Enter your Bugzilla directory and run:
+
+:command:`bzr info`
+
+and look at the Location: section of the output.
+If it says "light checkout root" then run:
+
+:command:`bzr -Ossl.cert_reqs=none switch https://bzr.bugzilla.org/bugzilla/$VERSION`
+
+Alternatively, if it says "branch root" or "checkout root" then run:
+
+:command:`bzr -Ossl.cert_reqs=none pull --remember https://bzr.bugzilla.org/bugzilla/$VERSION`
+
+Replace $VERSION with the two-digit version number of your current
+Bugzilla, e.g. "4.2" (see below for how to find that).
+
 .. include:: migrating-from-2.inc.rst