Scheduled Backup Fails if build is in queue

We have a scheduled backup set to run every 3 days, and it pretty much always fails with:

2007-10-21 01:00:00,021 ERROR [QuartzScheduler_Worker-9] [ScheduledBackupJob] com.atlassian.bamboo.migration.ImportExportException: Bamboo is busy. Please wait until all builds in queue have f
inished or manually stop the builds.
com.atlassian.bamboo.migration.ImportExportException: Bamboo is busy. Please wait until all builds in queue have finished or manually stop the builds.
at com.atlassian.bamboo.migration.ImportExportManagerImpl.bambooExport(ImportExportManagerImpl.java:49)
at com.atlassian.bamboo.configuration.ScheduledBackupJob.execute(ScheduledBackupJob.java:68)
at org.quartz.core.JobRunShell.run(JobRunShell.java:203)
at com.atlassian.bamboo.quartz.SystemAuthorizedThreadPool$1.run(SystemAuthorizedThreadPool.java:36)
at org.quartz.simpl.SimpleThreadPool$WorkerThread.run(SimpleThreadPool.java:520)

This is probably because we have a build set to run early in the morning that takes a few hours. The scheduled backup should wait until the build is finished and then do a backup instead of failing immediately and never performing the backup.