Initially Cruisecontrol was running perfectly. We had changed from stash to github url. Upon changing we always endup with error 'CheckForModifications'. Not sure whether the credentails/url has been cached.
Error Message: Source control operation failed: fatal: remote error: CAPTCHA required. Your stash account has been marked as requiring a CAPTCHA to be solved before you may login agin. This is typically caused by too many attempts to login with an incorrect password. The required CAPTCHA prevents your SCM client from accessing Stash until it is solved, even if you enter your password correctly.
It sounds like it is still trying to access Stash. to change the remote url, go to your working directory and use
git remote set-url origin https://github.com/user/repo.git