Don't forget to rescan MOH files for cached realtime classes

Realtime MOH class caching was implemented because without it, you would build
a completely new MOH class and would start the music over at the beginning each
time hold was pressed in a conversation. Unfortunately, this broke re-scanning
for file changes for realtime MOH classes. This patch corrects that issue.

(closes issue ASTERISK-18039)
Review: https://reviewboard.asterisk.org/r/1579/
........

Merged revisions 344899 from http://svn.asterisk.org/svn/asterisk/branches/1.8


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/10@344900 65c4cc65-6c06-0410-ace0-fbb531ad65f3

res/res_musiconhold.c

@@ -1522,6 +1522,7 @@ static int local_ast_moh_start(struct ast_channel *chan, const char *mclass, con
 			}
 		} else {
 			ast_variables_destroy(var);
+			var = NULL;
 		}
 	}
 
@@ -1529,6 +1530,14 @@ static int local_ast_moh_start(struct ast_channel *chan, const char *mclass, con
 		return -1;
 	}
 
+	/* If we are using a cached realtime class with files, re-scan the files */
+	if (!var && ast_test_flag(global_flags, MOH_CACHERTCLASSES) && mohclass->realtime && !strcasecmp(mohclass->mode, "files")) {
+		if (!moh_scan_files(mohclass)) {
+			mohclass = mohclass_unref(mohclass, "unreffing potential mohclass (moh_scan_files failed)");
+			return -1;
+		}
+	}
+
 	ast_manager_event(chan, EVENT_FLAG_CALL, "MusicOnHold",
 		"State: Start\r\n"
 		"Channel: %s\r\n"