Archive mode broken after the latest updates

[Guido Soranzio]

After the latest updates, while trying to install an archived port,
the following error message is displayed:

DEBUG: Executing com.apple.main (unrar)
DEBUG: Found TGZ archive: /opt/local/var/db/dports/packages/darwin/ 
powerpc/unrar-3.7.4_0.powerpc.tgz
--->  Unpacking tgz archive for unrar 3.7.4_0
DEBUG: Executing com.apple.unarchive (unrar)
DEBUG: Using /usr/bin/tar
DEBUG: Using /usr/bin/gzip
--->  Extracting unrar-3.7.4_0.powerpc.tgz
DEBUG: Environment:
DEBUG: Assembled command: 'cd "/opt/local/var/db/dports/build/ 
_opt_local_var_db_dports_sources_rsync.rsync.darwinports.org_dpupdate_dp 
orts_archivers_unrar/work/destroot" && /usr/bin/tar -xvpf -'
DEBUG: Executing unarchive_finish
Error: Target com.apple.unarchive returned: error copying "/opt/local/ 
var/db/dports/build/ 
_opt_local_var_db_dports_sources_rsync.rsync.darwinports.org_dpupdate_dp 
orts_archivers_unrar/work/destroot/+STATE": no such file or directory
Warning: the following items did not execute (for unrar):  
com.apple.activate com.apple.unarchive com.apple.fetch  
com.apple.extract com.apple.checksum com.apple.patch  
com.apple.configure com.apple.build com.apple.destroot  
com.apple.archive com.apple.install
Error: Status 1 encountered during processing.

I have recompiled MacPorts 1.4 from the MacOSForge's sources and the
archive mode works if you limit to only sync. After selfupdating
to MacPorts 1.4.3, the error occurs again.