Broken DDS support

[Dragon31337]

Imagemagick does not support DDS porperly most of the time I get
convert Out_dispatch_3.dds Out_dispatch_3.jpg
convert.EXE: Improper image header `Out_dispatch_3.dds' @ error/dds.c/ReadDDSImage/280.
convert.EXE: no images defined `Out_dispatch_3.jpg' @ error/convert.c/ConvertImageCommand/3044or
identify -verbose Out_dispatch_2.dds
identify.EXE: unable to open image `Out_dispatch_2.dds': No such file or directory @ error/blob.c/OpenBlob/2622.

That is just simple RGBA8888 1920x1200 texture.
Sample DDS is here: http://filestore.com.ua/?d=C228CD9F9

Other DDS tools are able to open this file without any issues.

Reproducible even on latest builds ImageMagick-6.7.8-7-Q16