qt4-mac-mysql55-plugin subports conflict but MacPorts doesn't tell me

[ryandesign (Ryan Carsten Schmidt)]

Oddly, although qt4-mac-mysql55-plugin and its subports declare conflicts with one another:

$ port info qt4-mac-mariadb-plugin
qt4-mac-mariadb-plugin @4.8.5 (aqua, databases)
Variants:             debug, (+)universal

Description:          Qt MySQL database plugin for mariadb
Homepage:             http://qt.nokia.com/

Build Dependencies:   pkgconfig
Library Dependencies: qt4-mac, mariadb
Conflicts with:       qt4-mac-mysql5-plugin, qt4-mac-mysql51-plugin, qt4-mac-mysql55-plugin,
                      qt4-mac-mysql56-plugin, qt4-mac-percona-plugin
Platforms:            macosx
License:              LGPL-2.1 GPL-3
Maintainers:          michaelld@macports.org, pixilla@macports.org, openmaintainer@macports.org

$ port installed qt4-mac-mysql5-plugin
The following ports are currently installed:
  qt4-mac-mysql5-plugin @4.8.5_0 (active)

MacPorts doesn't seem to recognize this, and allows me to install another subport anyway, without letting me know beforehand that there will be an activation conflict:

--->  Fetching distfiles for qt4-mac-mariadb-plugin
--->  Verifying checksums for qt4-mac-mariadb-plugin
--->  Extracting qt4-mac-mariadb-plugin
--->  Configuring qt4-mac-mariadb-plugin
--->  Building qt4-mac-mariadb-plugin
--->  Staging qt4-mac-mariadb-plugin into destroot
--->  Installing qt4-mac-mariadb-plugin @4.8.5_0+universal
--->  Activating qt4-mac-mariadb-plugin @4.8.5_0+universal
Error: org.macports.activate for port qt4-mac-mariadb-plugin returned: Image error: /opt/local/share/qt4/plugins/sqldrivers/libqsqlmysql.dylib is being used by the active qt4-mac-mysql5-plugin port.  Please deactivate this port first, or use 'port -f activate qt4-mac-mariadb-plugin' to force the activation.
Error: Failed to install qt4-mac-mariadb-plugin

[pixilla (Bradley Giesbrecht)]

See r113222