Gnutar not found during MacPorts operations.

fmbp:~ root# port -v upgrade outdated
--->  Extracting gperf
--->  Extracting gperf-3.0.4.tar.gz
sh: /usr/bin/gnutar: No such file or directory
gzip: error writing to output: Broken pipe

The permanent solutions is to reinstall MacPorts but there are other ways too. My favorite is:
Edit the variable tar_command from the files below from:
variable tar_command "/usr/bin/gnutar --no-same-owner"
to
variable tar_command "/usr/bin/tar -o"

Before:

fmbp:~ root# grep tar_command /opt/local/share/macports/Tcl/macports1.0/macports_autoconf.tcl
    variable tar_command "/usr/bin/gnutar --no-same-owner"
fmbp:~ root# grep tar_command /opt/local/share/macports/Tcl/port1.0/port_autoconf.tcl
	variable tar_command "/usr/bin/gnutar --no-same-owner"

After:

fmbp:~ root# grep tar_command /opt/local/share/macports/Tcl/macports1.0/macports_autoconf.tcl
    variable tar_command "/usr/bin/tar -o"
fmbp:~ root# grep tar_command /opt/local/share/macports/Tcl/port1.0/port_autoconf.tcl
	variable tar_command "/usr/bin/tar -o"