Do not force promise.

Additionaly support slapos_update_promise

slapos/recipe/build.py

@@ -104,10 +104,14 @@ def guessPlatform():
 
 class Script:
   """Free script building system"""
-  def _checkPromise(self, location):
+  def _checkPromise(self, promise_key, location):
+    promise_text = self.options.get(promise_key)
+    if promise_text is None:
+      self.logger.warning('Promise %r not defined' % promise_key)
+      return True
     promise_problem_list = []
     a = promise_problem_list.append
-    for promise in self.options['slapos_promise'].split('\n'):
+    for promise in promise_text.split('\n'):
       promise = promise.strip()
       if not promise:
         continue
@@ -279,7 +283,7 @@ class Script:
       env = self.getEnvironment()
       exec self.options['script']
       try:
-        self._checkPromise(self.options['location'])
+        self._checkPromise('slapos_promise', self.options['location'])
       except Exception:
         if os.path.exists(self.options['location']):
           self.logger.info('Removing location %r because of error' %
@@ -300,6 +304,11 @@ class Script:
     try:
       env = self.getEnvironment()
       exec self.options['update_script']
+      try:
+        self._checkPromise('slapos_update_promise', self.options['location'])
+      except Exception:
+        self.logger.info('Keeping location %r during update' % self.options['location'])
+        raise
     finally:
       for d in self.cleanup_dir_list:
         if os.path.exists(d):