We need to create an oe-selftest test for "devtool modify virtual/kernel" to verify at least the following:

1) That it checks out the source correctly

2) That you can build the kernel successfully 

3) That the resulting configuration is the same as what you get when you haven't run devtool modify on it

4) That you can make changes to the code and those get incorporated in a subsequent build

5) That you can make changes to the configuration and those get incorporated in a subsequent build