System Information
Windows 10 64 bit, NVidia GTX 950m

Blender Version
Broken: (example: 2.69.7 4b206af, see splash screen)
2.78c

Short description of error
Curve modifier when added after an array modifier appears to make it impossible to size objects correctly.

Exact steps for others to reproduce the error
Attached zip file contains two blender files with identical 3D scenes (one path curve + a cube array) along (1) the X axis and (2) the Y axis.

In both cases, if you try to change the dimensions of the cube array (by pressing N to display the transform panel, in order to enter new dimension values), the new dimension values that are entered do not register correctly (after pressing ENTER), while the Z axis size value changes arbitrarily (after trying to enter a new X or Y value, unsuccessfully).

It is understood that the dimensions of a single 3D object should be changed while in Edit Mode (e.g. by scaling), rather than through the transform panel when in Object Mode. Nevertheless, the weird and unpredictable behavior reported here should be corrected.

This issue may be related to https://developer.blender.org/T51020.

(Note: At some point while developing the blend-files attached, it appeared that the Y axis version presented additional problems, but I cannot replicate such issues any more.)