Index: sitescripts/extensions/bin/createNightlies.py
===================================================================
--- a/sitescripts/extensions/bin/createNightlies.py
+++ b/sitescripts/extensions/bin/createNightlies.py
@@ -60,16 +60,23 @@
     """
 
     def __init__(self, config):
         """
           Creates a NightlyBuild instance; we are simply
           recording the configuration settings here.
         """
         self.config = config
+        try:
+            self.bookmark = self.config.get(
+                'extensions', 'abp{}_bookmark'.format(self.config.type)
+            )
+        except ConfigParser.NoOptionError:
+            self.bookmark = 'master'
+
         self.revision = self.getCurrentRevision()
         try:
             self.previousRevision = config.latestRevision
         except:
             self.previousRevision = '0'
         self.buildNum = None
         self.tempdir = None
         self.outputFilename = None
@@ -78,18 +85,18 @@
     def hasChanges(self):
         return self.revision != self.previousRevision
 
     def getCurrentRevision(self):
         """
             retrieves the current revision ID from the repository
         """
         command = [
-            'hg', 'id', '-i', '-r', 'default', '--config', 'defaults.id=',
-            self.config.repository
+            'hg', 'id', '-i', '-r', self.bookmark, '--config',
+            'defaults.id=', self.config.repository
         ]
         return subprocess.check_output(command).strip()
 
     def getCurrentBuild(self):
         """
             calculates the (typically numerical) build ID for the current build
         """
         command = ['hg', 'id', '-n', '--config', 'defaults.id=', self.tempdir]
@@ -98,33 +105,36 @@
             build += '-beta'
         return build
 
     def getChanges(self):
         """
           retrieve changes between the current and previous ("first") revision
         """
 
-        command = ['hg', 'log', '-R', self.tempdir, '-r', 'tip:0',
-                   '-b', 'default', '-l', '50', '--encoding', 'utf-8',
-                   '--template', '{date|isodate}\\0{author|person}\\0{rev}\\0{desc}\\0\\0',
-                   '--config', 'defaults.log=']
+        command = [
+            'hg', 'log', '-R', self.tempdir, '-r', self.bookmark + ':0',
+            '-b', 'default', '-l', '50', '--encoding', 'utf-8', '--template',
+            '{date|isodate}\\0{author|person}\\0{rev}\\0{desc}\\0\\0',
+            '--config', 'defaults.log='
+        ]
         result = subprocess.check_output(command).decode('utf-8')
 
         for change in result.split('\x00\x00'):
             if change:
                 date, author, revision, description = change.split('\x00')
                 yield {'date': date, 'author': author, 'revision': revision, 'description': description}
 
     def copyRepository(self):
         """
           Create a repository copy in a temporary directory
         """
         self.tempdir = tempfile.mkdtemp(prefix=self.config.repositoryName)
-        command = ['hg', 'clone', '-q', self.config.repository, '-u', 'default', self.tempdir]
+        command = ['hg', 'clone', '-q', self.config.repository,  '-u',
+                   'default', self.tempdir]
         subprocess.check_call(command)
 
         # Make sure to run ensure_dependencies.py if present
         depscript = os.path.join(self.tempdir, 'ensure_dependencies.py')
         if os.path.isfile(depscript):
             subprocess.check_call([sys.executable, depscript, '-q'])
 
     def writeChangelog(self, changes):