[postgis-users] unable to assign hole to a shell

[Patrick Valsecchi]

Hi,

I was trying to play with polygons on PostGIS and I found this one to be quite 
troublesome:

POLYGON((9.50351715087891 47.3943328857422,9.50386047363281 
47.3943328857422,9.50351715087891 47.3943328857422,9.50248718261719 
47.3943328857422,9.50214385986328 47.3939895629883,9.50180053710938 
47.3943328857422,9.50145721435547 47.3939895629883,9.50111389160156 
47.3936462402344,9.50145721435547 47.3936462402344,9.50145721435547 
47.3939895629883,9.50214385986328 47.3939895629883,9.50248718261719 
47.3939895629883,9.50386047363281 47.3943328857422,9.50351715087891 
47.3943328857422))

When given to st_buffer(), it will throw this error:

NOTICE:  AssertionFailedException: unable to assign hole to a shell
ERROR:  GEOS buffer() threw an error!

I don't understand... if you look at it, it looks like an armless polygon. 
More details (picture) can be found here:
http://patrick.blog.thus.ch/?p=8

I'am using PostgresQL 8.2.4 on a Debian install with:
POSTGIS="1.3.1" GEOS="2.2.3-CAPI-1.1.1" PROJ="Rel. 4.5.0, 22 Oct 2006" 
USE_STATS

Does anybody have an idea on what my problem is?

Thanks