B: expand path when plumbing files

When we plumb a file, we open it in the current working
directory if it exists. However, if it doesn't exist,
we end up opening it relative to the editor's working
directory.

Expanding the path to works around this issue.

rc/bin/B

@@ -10,10 +10,9 @@ if(~ $#* 0){
 	exit usage
 }
 
-if(test -f /mnt/plumb/edit || test -f /mnt/term/mnt/plumb/edit){
-	for(i)
+wdir=`{pwd}
+for(i){
+	if(! ~ $i /*)
+		i=$wdir/$i
 	plumb -s B -d edit $i
-	exit
 }
-
-echo 'no plumber' >[1=2]