Don't write creationDate & updateDate unless specified

src/cal_tools/files.py

@@ -310,16 +310,14 @@ class DataFile(h5py.File):
             if sequence is None:
                 sequence = self.__sequence
 
-        if creation_date is None:
-            creation_date = datetime.now()
-
         if update_date is None:
             update_date = creation_date
 
         md_group = self.require_group('METADATA')
-        md_group.create_dataset(
-            'creationDate', shape=(1,),
-            data=creation_date.strftime('%Y%m%dT%H%M%SZ').encode('ascii'))
+        if creation_date is not None:
+            md_group.create_dataset(
+                'creationDate', shape=(1,),
+                data=creation_date.strftime('%Y%m%dT%H%M%SZ').encode('ascii'))
         md_group.create_dataset('daqLibrary', shape=(1,),
                                 data=daq_library.encode('ascii'))
         md_group.create_dataset('dataFormatVersion', shape=(1,), data=b'1.2')
@@ -360,9 +358,10 @@ class DataFile(h5py.File):
             'runNumber', shape=(1,), dtype=np.uint32, data=run)
         md_group.create_dataset(
             'sequenceNumber', shape=(1,), dtype=np.uint32, data=sequence)
-        md_group.create_dataset(
-            'updateDate', shape=(1,),
-            data=update_date.strftime('%Y%m%dT%H%M%SZ').encode('ascii'))
+        if update_date is not None:
+            md_group.create_dataset(
+                'updateDate', shape=(1,),
+                data=update_date.strftime('%Y%m%dT%H%M%SZ').encode('ascii'))
 
 
 class ControlSource(h5py.Group):