The one I attached was created in VS2013.
I also have another project created in VS2012 which does not have the #VisualStudio line. Opening it under VS2013 DID NOT add the #VisualStudio comment, basically left it unaltered.
To make matters worse, I currently work in an environment that is routinely using 6, 2012, 2013 and soon 2015, with some 2012 solutions that HAVE to be used with 2012 (last one with DBCS), and some that are used with 2013.
I know that this is messy, that's why MS introduced the selector which is supposedly able to figure all this out.
I really wouldn't mind if you would pop up a box and ask me which VS version I wanted to use with the solution (the first time, anyway).
Marcel