One-line change to fix coinc.xml file creation.

The xmldoc write was never being closed on event upload and so
the original copy of the coinc.xml file was never created. Fixed
now.

gracedb/events/serialize.py

@@ -90,9 +90,11 @@ def write_output_files(root_dir, xmldoc, log_content, \
     # Write xml-formatted coinc table
     # We do it this way instead of using create_versioned_file since the
     # xmldoc is designed to write to a file object.
+
     file_path = os.path.join(root_dir, xml_fname)
     f = VersionedFile(file_path, 'w')
     xmldoc.write(f.file)
+    f.close()
 
     # Write log file
     create_versioned_file(log_fname, root_dir, log_content)