OpenOffice.org Calc crashes whenever the user attempts to open a spreadsheet
with a nonstandard filename extension, or without a filename extension.  This
problem occurs quite often when opening a spreadsheet which has been dynamically
generated and named by a web server.  For example, the popular MicroStrategy web
application lets users download dynamically generated HTML and Excel
spreadsheets, but it doesn't give these resources a filename extension.

Reproducibility: Always

Steps to reproduce:
1. Take an Excel (.xls) or HTML (.html) spreadsheet, and rename it to remove the
filename extension, or give it a nonstandard extension (such as .foo)
2. Use OpenOffice.org Calc to open the renamed file.  This can be done by via
the command line (e.g., "/usr/bin/oocalc some_spreadsheet.foo") or by File->Open
and selecting it with the file selection dialog.

Observed behaviour:
3. The OpenOffice.org Document Recovery pops up to say, "Due to an unexpected
error, OpenOffice.org crashed..."

Expected behaviour:
3. OpenOffice.org Calc should have successfully opened the file.

I think this problem may be unique to Calc.  I'm not able to reproduce the
problem in Writer.