Qt plugins won't load from mapped drives

When trying to load a plugin from a mapped virtual drive on Windows, then the plugin will not load.

Steps to reproduce:

1) Create a mapped drive under Control Panel/Administrative Tools/Computer ManageMent/Disk Management. For example, if having a drive D:\ where Qt is installed, then right click this drive and select "Change Drive Letter and Paths for D". Then select the "Add" button and add the path "C:\driveTest".

2) Open a command prompt and go to c:\driveTest\qtVersion\examples\itemviews\puzzle

3) Create an imageformats directory in the debug directory of the puzzle example and put the jpeg plugin inside it.

4) Add a line similar to the following to main()

app.addLibraryPath("C:\\driveTest\\\\4.7.0\\examples\\itemviews\\puzzle
debug");

5) Run the example and the plugin will not load