Step 1) Create a jboss server
step 2) create a dynamic web project
step 3) open server editor for server from 1)
step 4) set server to view all modules
step 5) modify the deploy and the temp deploy folders
step 6) save editor
step 7) add web project to server, initiate full publish
step 8) verify whether or not the file copy went to the right temp folder (FAIL)

Details that will be helpful to actually catching the bug are:
1) you will want your server to use server based deployment (middle radio)
2) You will want to customize the per-module deploy folder to be on a different file system
3) You will want the per-module temp folder to be on the same fs as the per-module deploy folder

The file-copy mechanism initially copies to the tempDeployFolder, then does a renameTo the final destination. The renameTo fails if the source and destination are on different Filesystems. To force the bug, you will want to ensure the default deploy / temp deploy (in the disabled text boxes) is different from the ones you type in the server editor / column viewer.