Windows 7 64-bit, GTX-580 GPU
Broken: buildbot 2.71.5 ea07d93
Worked: 2.70a official
Short description of error
When the scene scale is set to something other than 1 (when the units are set to meters or imperial,) and then the units are switched back to "none" without changing the scene scale back to 1, any translations input from the keyboard will be assumed to be in meters, not Blender Units.
So if the scene scale is set to, say, 0.2, and you select an object (or vertices/edges/faces in edit mode,) and move it up along the z-axis by 1 (by hitting the keys "g", "z", "1", and "enter", not by dragging it,) the object will be moved up by 5.0 units; that is, by 1/(scene scale), or 1 m. The translation vector displayed in the toolbar will read "0.000, 0.000, 5.000".
Exact steps for others to reproduce the error
"With the default cube selected, hit g z 1 enter.
That should translate the cube upward along the z-axis by 1 unit. Instead, it translates the cube up by 1/0.2 units, where 0.2 is the scene scale, which you can see if you switch the scene units to meters.
Switch the units to meters, then hit g z -1 enter. That will move the cube down by 1 meter, and will put it exactly back at the origin.
Switch the units to feet, and g z 1 enter will move it up by 1', not 1 meter."