Null list in catenation if sysname is not set

Notes:
Wed May 2 12:28:13 EDT 2007 geoff
Wed May 2 12:30:16 EDT 2007 geoff
    termrc and termrc.local must co-ordinate to ensure
    that $sysname is set before its first use.
    in most cases, starting cs will suffice; otherwise
    make arrangements in termrc.local, using environment
    variables from plan9.ini if necessary.
    trying to continue running with $sysname unset
    will trip up other programs.


Reference: /n/sources/patch/sorry/termrc-error
Date: Sun Apr 29 14:28:28 CES 2007
Signed-off-by: lawler.jack@gmail.com
Reviewed-by: geoff

--- /rc/bin/termrc	Sun Apr 29 14:27:49 2007
+++ /rc/bin/termrc	Sun Apr 29 14:27:48 2007
@@ -27,7 +27,7 @@
 sysname=`{cat /dev/sysname}
 
 # machine specific startup (e.g., for devices not probed)
-if(test -e /cfg/$sysname/termrc)
+if(~ $#sysname 1 && ! ~ $#sysname '' && test -e /cfg/$sysname/termrc)
 	. /cfg/$sysname/termrc
 
 # start IP on the LAN, if not already configured.  diskless terminals