Fetch libregexp-common-perl from Debian unstable.

The 2011041701-3 version of this package fixes bugs/msva_does_not_use_configured_keyserver.

config/chroot_apt/preferences

@@ -27,6 +27,10 @@ Package: libio-socket-ssl-perl
 Pin: origin backports.debian.org
 Pin-Priority: 999
 
+Package: libregexp-common-perl
+Pin: release o=Debian,a=unstable
+Pin-Priority: 999
+
 Package: macchanger
 Pin: release o=Debian,a=unstable
 Pin-Priority: 999