Description of problem:
On spacewalk 1.5 and postgresql 8.4 installation, when I go to Systems --> "SystemName" --> Provisionning --> Snapshots and the I click on any entry, I get the following traceback:
Error message:
  RHN::Exception: DBD::Pg::st execute failed: ERROR:  syntax error at or near "MINUS" at character 869

  RHN::DB /usr/lib/perl5/vendor_perl/5.8.8/RHN/DB.pm 228 RHN::Exception::DB::throw
  RHN::DB::st /usr/lib/perl5/vendor_perl/5.8.8/RHN/DB.pm 564 RHN::DB::handle_error
  RHN::DB::DataSource /usr/lib/perl5/vendor_perl/5.8.8/RHN/DB/DataSource.pm 75 RHN::DB::st::execute_h
  RHN::DataSource /usr/lib/perl5/vendor_perl/5.8.8/RHN/DataSource.pm 108 RHN::DB::DataSource::run_query
  RHN::DB::SystemSnapshot /usr/lib/perl5/vendor_perl/5.8.8/RHN/DB/SystemSnapshot.pm 164 RHN::DataSource::execute_query
  Sniglets::Snapshot /usr/lib/perl5/vendor_perl/5.8.8/Sniglets/Snapshot.pm 119 RHN::DB::SystemSnapshot::package_list_is_servable
  PXT::Parser /usr/lib/perl5/vendor_perl/5.8.8/PXT/Parser.pm 160 Sniglets::Snapshot::snapshot_details
  PXT::Parser /usr/lib/perl5/vendor_perl/5.8.8/PXT/Parser.pm 72 PXT::Parser::expand_tag
  PXT::ApacheHandler /usr/lib/perl5/vendor_perl/5.8.8/PXT/ApacheHandler.pm 510 PXT::Parser::expand_tags
  PXT::ApacheHandler /usr/lib/perl5/vendor_perl/5.8.8/PXT/ApacheHandler.pm 113 PXT::ApacheHandler::pxt_parse_data
  PXT::ApacheHandler /usr/lib/perl5/vendor_perl/5.8.8/PXT/ApacheHandler.pm 113 (eval)
  main -e 0 PXT::ApacheHandler::handler
  main -e 0 (eval)


Version-Release number of selected component (if applicable): Spacewalk 1.5


How reproducible: 
go to Systems --> "SystemName" --> Provisionning --> Snapshots and click on any entry

  
Actual results:
Error 500

Expected results:
The page displays correctly

Additional info:
Logging all SQL queries, here is the query that fails:
ERROR:  syntax error at or near "MINUS" at character 869
STATEMENT:
        SELECT PN.id AS NAME_ID,
               PE.id AS EVR_ID,
               PN.name AS NAME,
               PE.version AS VERSION,
               PE.release AS RELEASE,
               PE.epoch AS EPOCH,
               PN.name || '-' || evr_t_as_vre_simple(PE.evr) AS NVRE,
               UPPER(PN.name || '-' || evr_t_as_vre_simple(PE.evr)) AS U_NVRE
          FROM rhnPackageName PN,
               rhnPackageEVR PE,
               rhnPackageNEVRA PNEVRA,
               rhnSnapshotPackage SP,
               rhnSnapshot S
         WHERE S.id = $1
           AND S.server_id = $2
           AND S.id = SP.snapshot_id
           AND SP.nevra_id = PNEVRA.id
           AND PNEVRA.name_id = PN.id
           AND NOT EXISTS (SELECT 1 FROM rhnPackageSyncBlacklist PSB WHERE
                             PSB.package_name_id = PN.id AND org_id is NULL OR org_id = $3)
           AND PNEVRA.evr_id = PE.id
           AND NOT EXISTS (
        SELECT 1 FROM rhnServerPackage SP
         WHERE SP.server_id = $2
           AND SP.name_id = PN.id
           AND SP.evr_id = PE.id
        )
        MINUS
        SELECT PN.id AS NAME_ID,
               PE.id AS EVR_ID,
               PN.name AS NAME,
               PE.version AS VERSION,
               PE.release AS RELEASE,
               PE.epoch AS EPOCH,
               PN.name || '-' || evr_t_as_vre_simple(PE.evr) AS NVRE,
               UPPER(PN.name || '-' || evr_t_as_vre_simple(PE.evr)) AS U_NVRE
          FROM rhnPackageName PN,
               rhnPackageEVR PE,
               rhnPackage P,
               rhnChannelPackage CP,
               rhnSnapshotChannel SC
         WHERE SC.snapshot_id = $1
           AND SC.channel_id = CP.channel_id
           AND CP.package_id = P.id
           AND P.name_id = PN.id
           AND P.evr_id = PE.id
        ORDER BY 8