Jenkins loses workspaces periodically, triggers unwanted build

I have builds set up in Jenkins that use custom workspaces (for the purpose of having no spaces in the path names), that use SCM (git) polling to check for changes. However, in what seems like exactly every 24 hours, I see a triggered build that has this polling log:

Started on Jun 13, 2011 5:21:32 PM
No workspace is available, so can't check for updates.
Scheduling a new build to get a workspace.
Done. Took 1 ms
Changes found

It appears to be scheduling a build simply to obtain a workspace (so开发者_如何学Pythonmething I expressly do not want to happen) even though nothing has been committed to git. I have unticked the option to remove old builds, do not have a periodic build set up, and use SCM polling once a minute.

I'm stumped and can't provide more detail than this - other than I know the workspace exists on the machine. Is there any way to stop this from happening other than ACTUAL commits to git?

The changelog for version 1.1.12 indicates that a workspace is no longer required for polling. Upgrading to this version of the plugin fixed this problem for us.