can't read "variant_installed": no such variable

[Ryan Schmidt]

Trying to upgrade rpm51 running MacPorts 1.7 release branch r47786 I  
get this curious message; any ideas? I was able to upgrade other  
ports (that have no variants selected) successfully. Perhaps it has  
to do with the fact that this port has an autoselected platform  
variant (+macosx) but no other variants.


$ port installed rpm51
The following ports are currently installed:
   rpm51 @5.1.6_2+macosx (active)
$ port -ux upgrade rpm51
can't read "variant_installed": no such variable
     while executing
"ui_debug "$iname ${version_installed}_${revision_installed}$ 
{variant_installed} is installed""
     (procedure "upgrade" line 136)
     invoked from within
"upgrade $d $i $variationslist [array get options] depscache"
     (procedure "macports::upgrade" line 172)
     invoked from within
"macports::upgrade $portname "port:$portname" [array get variations]  
[array get options]"
     ("uplevel" body line 9)
     invoked from within
"uplevel 1 $block"
     (procedure "foreachport" line 16)
     invoked from within
"foreachport $portlist {
         # Merge global variations into the variations specified for  
this port
         foreach { variation value } [array get g..."
     (procedure "action_upgrade" line 6)
     invoked from within
"$action_proc $action $portlist [array get global_options]"
     (procedure "process_cmd" line 86)
     invoked from within
"process_cmd $remaining_args"
     invoked from within
"if { [llength $remaining_args] > 0 } {

     # If there are remaining arguments, process those as a command

     # Exit immediately, by default, unless..."
     (file "/mp/bin/port" line 3241)
$