service: schedule cleanup of PID hashmaps when we now longer have mai…

…n_pid and we are in container

RHEL-only

Resolves: RHEL-5863

src/core/service.c

@@ -34,6 +34,7 @@
 #include "string-table.h"
 #include "string-util.h"
 #include "strv.h"
+#include "virt.h"
 #include "unit-name.h"
 #include "unit.h"
 #include "utf8.h"
@@ -3535,7 +3536,7 @@ static void service_sigchld_event(Unit *u, pid_t pid, int code, int status) {
          * detect when the cgroup becomes empty. Note that the control process is always
          * our child so it's pointless to watch all other processes. */
         if (!control_pid_good(s))
-                if (!s->main_pid_known || s->main_pid_alien)
+                if (!s->main_pid_known || s->main_pid_alien || (s->main_pid == 0 && detect_container() > 0))
                         (void) unit_enqueue_rewatch_pids(u);
 }