Default mach.bat to using py -2.
Default mach.bat to using py -2.

Servo already assumes the user has Python, this is the primary
way to make sure that Python 2 is preferred, and you should
get a sensible error message if you have python 3 but not 2.

But first, check that py.exe exists because if a system has only
Python 2.x only, it won't have it. If it doesn't, then try python.exe.

DominoTree/servo,DominoTree/servo,paulrouget/servo,nnethercote/servo,paulrouget/servo,KiChjang/servo,paulrouget/servo,nnethercote/servo,pyfisch/servo,nnethercote/servo,DominoTree/servo,pyfisch/servo,KiChjang/servo,DominoTree/servo,KiChjang/servo,paulrouget/servo,saneyuki/servo,saneyuki/servo,larsbergstrom/servo,KiChjang/servo,larsbergstrom/servo,larsbergstrom/servo,splav/servo,notriddle/servo,KiChjang/servo,emilio/servo,DominoTree/servo,emilio/servo,pyfisch/servo,emilio/servo,splav/servo,notriddle/servo,nnethercote/servo,DominoTree/servo,emilio/servo,pyfisch/servo,splav/servo,emilio/servo,pyfisch/servo,notriddle/servo,saneyuki/servo,paulrouget/servo,DominoTree/servo,paulrouget/servo,KiChjang/servo,KiChjang/servo,pyfisch/servo,pyfisch/servo,paulrouget/servo,nnethercote/servo,saneyuki/servo,splav/servo,larsbergstrom/servo,pyfisch/servo,saneyuki/servo,larsbergstrom/servo,paulrouget/servo,nnethercote/servo,pyfisch/servo,saneyuki/servo,DominoTree/servo,larsbergstrom/servo,KiChjang/servo,notriddle/servo,notriddle/servo,splav/servo,nnethercote/servo,saneyuki/servo,emilio/servo,splav/servo,DominoTree/servo,larsbergstrom/servo,splav/servo,larsbergstrom/servo,larsbergstrom/servo,saneyuki/servo,KiChjang/servo,pyfisch/servo,notriddle/servo,nnethercote/servo,notriddle/servo,emilio/servo,DominoTree/servo,notriddle/servo,paulrouget/servo,splav/servo,KiChjang/servo,paulrouget/servo,nnethercote/servo,emilio/servo,saneyuki/servo,nnethercote/servo,notriddle/servo,splav/servo,emilio/servo,saneyuki/servo,notriddle/servo,splav/servo,emilio/servo,larsbergstrom/servo