Fix processes run with RemoteProcessSafeExit not receiving stdin

Since the process is run in the background through the wrapper bash
script, stdin was disabled there. By explicitly redirecting the bash
process stdin we make sure it is always able to read from it.

Change-Id: I6cb7979aae0a7457919f353cbeb4c3b78cdd4919

src/osmo_gsm_tester/core/remote.py

@@ -100,7 +100,7 @@ class RemoteHost(log.Origin):
                 echo "process ${term_child_pid} finished" >>$LOGFILE
             }
             prep_sighandler
-            $@ &
+            $@ <&0 &
             wait_sighandler
             """ % (wait_time_sec, wait_time_sec)
             f.write(r)