File checked out by build process and not checked in again in TFS 2010 Beta 1

While playing around with Team Build 2010 Beta 1, the build process running under the local service account checked out a file during a gated build and didn’t undo that.

I noticed it in the team explorer, one file kept having the checked-out icon, so I ran the following command in cmd:

tf.exe status $(ProjectDir) /user:* /recursive
Result:
ProductRepository.cs  edit   NT AUTHORITYNETWORK SERVICE C:\...ProductRepository.cs

Aha! To fix this I checked the build log for the workspace name and then tried to used tf.exe again to undo this checkout with no luck:

tf undo /workspace:"TFSURL_1_1;NT AUTHORITY\NETWORK SERVICE"
/server:http://tfsurl:8080 C:\...ProductRepository.cs

But this didn’t worked :(  tf undo didn’t found any checked out files.

Finally I could solve the problem with this hint from Robert Horvick on Twitter:

bubbafat@synclop If you haven’t got a Network Service build checkout solution yet - one way would be deleting the workspace. #tfs

So what I did was this:

tf workspace /delete /server:http://tfsurl:8080 "TFSURL_1_1;NT AUTHORITY\NETWORK SERVICE"

And everything worked fine again.