try, except replace with if...else

da/tm5/observationoperator.py

@@ -132,9 +132,9 @@ class TM5ObservationOperator(ObservationOperator):
         from string import join
         DaPlatForm = self.DaCycle.DaPlatForm
 
-        try:
+        if self.DaCycle.has_key('da.obsoperator.home'):
             os.chdir(self.DaCycle['da.obsoperator.home'])
-        except:
+        else:
             tm5_dir = os.path.split(self.DaCycle['da.obsoperator.rc'])[0]
             logging.warning('Guessing your TM5 root dir from the rc filename')
             logging.warning('Try adding a key da.obsoperator.home to your da.rc')