update: don't move the active bookmark if a rev is specified with -r

mercurial/commands.py

@@ -5701,7 +5701,7 b' def update(ui, repo, node=None, rev=None'
 
     # with no argument, we also move the current bookmark, if any
     movemarkfrom = None
-    if node is None or node == '':
+    if rev is None or node == '':
         movemarkfrom = repo['.'].node()
 
     # if we defined a bookmark, we have to remember the original bookmark name