Missing f.close() for the coinc.xml file in serialize.py
The changes between v2.7.1 and v2.8.0 introduced this bug (if I am understanding things correctly). The code in gracedb/events/serialize.py,
file_path = os.path.join(root_dir, xml_fname)
f = VersionedFile(file_path, 'w')
xmldoc.write(f.file)
is not followed by an f.close() line.
(I tracked this down after Leo noticed that the symlink was not created for the coinc.xml file, and the close method for a VersionedFile object is what creates/updates the symlink.)