Can't open binary grids created with ArcGIS 10

[cdestigter]

We're having problems with a binary grid created in ArcGIS 10. The equivalent grid created in 9.3 works fine.

With reference to the ​AIG format notes, it seems a few things are different than gdal expects:

• magic number is 00 00 27 0A FF FF FC 08, (not one of the two known magic numbers listed)
• tile type for many tiles (seems to be the ones with NODATA as the top left pixel) is 0x80 (not one of the known tile types in gdal/frmts/aigrid )
• RMinSize is 0x0 for each tile (seems odd? maybe okay)

The statistics are also a bit weird for the arcgis 10 grid (they're all zero):

    Min=1.000 Max=6.000 
    Minimum=0.000, Maximum=0.000, Mean=0.000, StdDev=0.000
    NoData Value=255
    Overviews: 1459x1000, 730x500, 365x250
    Metadata:
      STATISTICS_MINIMUM=0
      STATISTICS_MAXIMUM=0
      STATISTICS_MEAN=0
      STATISTICS_STDDEV=0

Not sure why there are a Min/Max but also different min/max statistics in the metadata.

With client permission, I've uploaded the two grids for testing purposes, as well as a small python script that reproduces the problem. They're here: ​http://dl.dropbox.com/u/2649727/gdal-aig-test.zip

The test script shows that after converting to GTiff, the ArcGIS 10 grid has nothing but zeroes in it, but the 9.3 grid has the correct data (values 1-6).

Tested on gdal 1.7.3