This patch fixes the error that happened when a cookie
remembered a non-existent data_source.
This was only really a problem when there was only one
possible data_source defined because the data_source
menu wouldn't pop up.
With this patch, it simply defaults to the default
data_sourse.
Apply the patch to .../Bio/GMOD/CMap/Config.pm .
Patch to .../Bio/GMOD/CMap/Config.pm