terminal/command_test: improved TestIssue387

The test in question tries to 'next' over a call to wg.Done, this is
not guaranteed to succeed, if the goroutine gets suspended after
wg.Done has notified the waiting group but before returning to
main.dostuff the program could quit before the goroutine is resumed.

pkg/terminal/command_test.go

@@ -458,7 +458,7 @@ func TestIssue387(t *testing.T) {
 					t.Fatalf("did not continue to expected position %d", pos)
 				}
 				pos++
-				if pos > 11 {
+				if pos >= 11 {
 					break
 				}
 			}