another transaction already in progress
appcfg.py rollback C:\path\to\my\app is the required command.
If you are using Java, the rollback command is same as above, but the path to the application should be to the application's target directory. Otherwise, rollback will fail.
I am using app engine launcher in windows and for some reason the last time i deployed my app, the transaction wouldn't finish, and now every time i try to deploy i get the error

another transaction by user is already in progress for app: s~ myapp, version 1

i have tried doing appcfg.py rollback, which brings up a python window, which then closes again almost immediately (i think it says error but it closes so fast i cant tell for sure)
i have tried doing appcfg.py rollback C:\ my\apps\directory\path - which leads to the same as above
i have tried doing C:\Program Files\Google\google_appengine appcfg.py rollback c:\my\app\path but windows then tells me it cant find C:\ program
and now im stuck for things to try?