[CMake] 3.4.1 installer overwrites Windows PATH system var

Thu Dec 3 11:04:10 EST 2015

Installing CMake on Windows (7, 64-bit) with the "add cmake to system
PATH for all users" option overwrote the contents of my PATH variable,
instead of appending to it.  This is horrible!  I don't know of any
way to recover my previous PATH value.

It also looks like this has been an issue in several previous versions:
  * https://cmake.org/Bug/view.php?id=10257
  * https://cmake.org/Bug/view.php?id=12875

Shouldn't there be a regression / sanity test case for this prior to
publishing a new version of the installer?