Only perform Verify in the same context as Run

Before this patch, verify is run twice when using fakemachine,
once as a normal user on the host, and then again as root on the
fakemachine. The issue is that a normal user may not be able to
invoke all the commands (e.g. just due to paths) that a superuser
can. In particular, debian installs debootstrap under /usr/sbin.

cmd/debos/debos.go

@@ -231,10 +231,12 @@ func main() {
 		}
 	}
 
-	for _, a := range r.Actions {
-		err = a.Verify(&context)
-		if exitcode = checkError(&context, err, a, "Verify"); exitcode != 0 {
-			return
+	if !runInFakeMachine {
+		for _, a := range r.Actions {
+			err = a.Verify(&context)
+			if exitcode = checkError(&context, err, a, "Verify"); exitcode != 0 {
+				return
+			}
 		}
 	}