PluginVersion tag missing from export xml

I installed a custom field plugin to our Jira 4.4 server using the in-app uploader. I then added that custom field to all issue types. I then did an export, and tried to do a project import into a dev server where I'd installed the plugin manually. The dev server cave an interesting message that the data had a custom field installed but that the plugin for that field had not been installed. (See screenshot, which also showed errors from greenhopper)

I checked the XML backup file, and there was no <PluginVersion> tag for the plugin I had upladed. I restarted the server, did a new backup, and the new file had the <PluginVersion> tag correctly included. Since this was a dev situation, there was not a big problem. However, if I'd wanted to do a project import into production, I'd have had to tweak my xml backup file by hand to recover my data.

(I'm marking this as major because it can result in backup files which cannot be used for project import.)