Inconsistent port upgrade behavior?

[Vincent Habchi]

Folks,

when I do "port outdated", I get this:

The following installed ports are outdated:
dbus                           1.4.18_0 < 1.4.20_1       


Now, if I try "port upgrade outdated", nothing happens:

--->  Scanning binaries for linking errors: 100.0%
--->  No broken files found.

How come?

Vincent