p5-dbd-pg: Variant postgresql90 conflicts with postgresql91

[Rodolfo Aramayo]

Hi,
I am observing the following:
##########################################################
--->  Computing dependencies for isl
--->  Fetching archive for isl
--->  Attempting to fetch isl-0.07_2.darwin_10.x86_64.tbz2 from
http://packages.macports.org/isl
--->  Attempting to fetch isl-0.07_2.darwin_10.x86_64.tbz2.rmd160 from
http://packages.macports.org/isl
--->  Installing isl @0.07_2
--->  Cleaning isl
--->  Computing dependencies for isl
--->  Deactivating cloog @0.16.3_2
--->  Deactivating isl @0.07_1
--->  Cleaning isl
--->  Activating isl @0.07_2
--->  Cleaning isl
Error: p5-dbd-pg: Variant postgresql90 conflicts with postgresql91
Error: Unable to open port: Error evaluating variants
To report a bug, follow the instructions in the guide:
    http://guide.macports.org/#project.tickets
##########################################################
Suggestions as to how to fix this?
Thanks

--R