MFC r196421:

Bugfix: all requests for creating vnets via vimage -c were always
  reported as failures, even if the actual library / system call
  would succeed, because error message would be reported if the return
  value from jail_setv() call was >= 0, and if not, then if that same
  value was < 0, i.e. always.  The correct behavior is to abort (only)
  if jail_setv() returns < 0.

  Approved by:  re (rwatson), julian (mentor)

Approved by:	re (rwatson)

tools/tools/vimage/vimage.c

@@ -252,7 +252,7 @@ main(int argc, char **argv)
 		exit(0);
 
 	case VI_CREATE:
-		if ((jid = jail_setv(JAIL_CREATE,
+		if (jail_setv(JAIL_CREATE,
 		    "name", argv[0],
 		    "vnet", NULL,
 		    "host", NULL,
@@ -260,9 +260,7 @@ main(int argc, char **argv)
 		    "allow.raw_sockets", "true",
 		    "allow.socket_af", "true",
 		    "allow.mount", "true",
-		    NULL)) >= 0)
-				break;
-		if (jid < 0)
+		    NULL) < 0)
 			break;
 		if (argc == 1)
 			exit(0);