seq: fixed a corner case in ASYNC put/get

If epicsEventTryWait succeeds, there could still be a previous request
pending that has timed out. This happens e.g. if the user code did not
call pvGetComplete resp. pvPutComplete. In that case we must reset the
request pointer to NULL in order to invalidate the request so it gets
ignored whenever it finally arrives.

src/seq/seq_if.c

@@ -120,6 +120,12 @@ epicsShareFunc pvStat epicsShareAPI seq_pvGet(SS_ID ss, VAR_ID varId, enum compT
 		switch (epicsEventTryWait(getSem))
 		{
 		case epicsEventWaitOK:
+			if (ss->getReq[varId] != NULL)
+			{
+				/* previous request timed out but user
+				   did not call pvGetComplete */
+				ss->getReq[varId] = NULL;
+			}
 			status = check_connected(dbch, meta);
 			if (status) return epicsEventSignal(getSem), status;
 			break;
@@ -392,6 +398,12 @@ epicsShareFunc pvStat epicsShareAPI seq_pvPut(SS_ID ss, VAR_ID varId, enum compT
 		switch (epicsEventTryWait(putSem))
 		{
 		case epicsEventWaitOK:
+			if (ss->putReq[varId] != NULL)
+			{
+				/* previous request timed out but user
+				   did not call pvPutComplete */
+				ss->putReq[varId] = NULL;
+			}
 			break;
 		case epicsEventWaitTimeout:
 			meta->status = pvStatERROR;