--- a/hgext/evolve.py	Mon May 18 13:58:57 2015 -0400
+++ b/hgext/evolve.py	Mon May 18 17:24:38 2015 -0700
@@ -1808,8 +1808,20 @@
                 newnode = newnode.parents()[0]
 
         if newnode.node() != wdp.node():
+            bookactive = bmactive(repo)
+            # Active bookmark that we don't want to delete (with -B option)
+            # we deactivate and move it before the update and reactivate it
+            # after
+            movebookmark = bookactive and not bookmark
+            if movebookmark:
+                bookmarks.deactivate(repo)
+                repo._bookmarks[bookactive] = newnode.node()
+                repo._bookmarks.write()
             commands.update(ui, repo, newnode.rev())
             ui.status(_('working directory now at %s\n') % newnode)
+            if movebookmark:
+                bookmarks.activate(repo, bookactive)
+
         # update bookmarks
         if bookmark:
             _deletebookmark(ui, marks, bookmark)

--- a/tests/test-prune.t	Mon May 18 13:58:57 2015 -0400
+++ b/tests/test-prune.t	Mon May 18 17:24:38 2015 -0700
@@ -40,8 +40,9 @@
   $ hg prune --user blah --date '1979-12-15' .
   1 changesets pruned
   0 files updated, 0 files merged, 1 files removed, 0 files unresolved
-  (leaving bookmark BABAR)
   working directory now at 47d2a3944de8
+  $ hg bookmark
+   * BABAR                     3:47d2a3944de8
   $ hg debugobsolete
   9d206ffc875e1bc304590549be293be36821e66c 0 {47d2a3944de8b013de3be9578e8e344ea2e6c097} (Sat Dec 15 00:00:00 1979 +0000) {'user': 'blah'}
 
@@ -50,6 +51,7 @@
   $ hg prune 1
   1 changesets pruned
   2 new unstable changesets
+  $ hg book -i BABAR
   $ hg debugobsolete
   9d206ffc875e1bc304590549be293be36821e66c 0 {47d2a3944de8b013de3be9578e8e344ea2e6c097} (Sat Dec 15 00:00:00 1979 +0000) {'user': 'blah'}
   7c3bad9141dcb46ff89abf5f61856facd56e476c 0 {1f0dee641bb7258c56bd60e93edfa2405381c41e} (*) {'user': 'test'} (glob)