--- a/hgext/reviewboard/server.py
+++ b/hgext/reviewboard/server.py
@@ -37,23 +37,22 @@ from mercurial.i18n import _
 from mercurial.node import (
     hex,
     nullid,
 )
 
 OUR_DIR = os.path.normpath(os.path.dirname(__file__))
 execfile(os.path.join(OUR_DIR, '..', 'bootstrap.py'))
 
-demandimport.disable()
-try:
-    import hgrb.proto
-except ImportError:
-    sys.path.insert(0, OUR_DIR)
-    import hgrb.proto
-demandimport.enable()
+with demandimport.deactivated():
+    try:
+        import hgrb.proto
+    except ImportError:
+        sys.path.insert(0, OUR_DIR)
+        import hgrb.proto
 
 testedwith = '3.3 3.4 3.5 3.6'
 
 cmdtable = {}
 command = cmdutil.command(cmdtable)
 
 
 # Capabilities the server requires in clients.