[tm] fix t_wait_no_more_branches() behaviour

Fixes #2891
Alternative to  #2898
Credits for the fix go to @man1207

(cherry picked from commit 14d900f)

modules/tm/t_fwd.c

@@ -1018,18 +1018,18 @@ static int dst_to_msg(struct sip_msg *s_msg, struct sip_msg *d_msg)
 }
 
 
-int t_wait_no_more_branches( struct cell *t)
+int t_wait_no_more_branches( struct cell *t, int extra)
 {
 	int b;
 
 	/* look back (in the set of active branches for a PHONY branch
-	 * that might contoll the EBR waiting. If found, update it
-	 * (the br_flags field), so that this is the lasr allowed injected
+	 * that might control the EBR waiting. If found, update it
+	 * (the br_flags field), so that this is the last allowed injected
 	 * branch (the max number of allowed branches is set to the current
 	 * number of branches) */
 	for ( b=t->nr_of_outgoings-1; b>=t->first_branch ; b-- ) {
 		if (t->uac[b].flags & T_UAC_IS_PHONY) {
-			t->uac[b].br_flags=t->nr_of_outgoings+1;
+			t->uac[b].br_flags=t->nr_of_outgoings+extra;
 			return 0;
 		}
 	}
@@ -1092,7 +1092,7 @@ int t_inject_branch( struct cell *t, struct sip_msg *msg, int flags)
 	}
 
 	if (flags&TM_INJECT_FLAG_LAST)
-		t_wait_no_more_branches(t);
+		t_wait_no_more_branches(t, 1/*the branch we will create*/);
 
 	/* generated the new branches, without branch counter reset */
 	rc = t_forward_nonack( t, &faked_req , NULL, 0, 1/*locked*/ );

modules/tm/t_fwd.h

@@ -66,7 +66,7 @@ int t_inject_ul_event_branch(void);
 
 int t_inject_branch( struct cell *t, struct sip_msg *msg, int flags);
 
-int t_wait_no_more_branches( struct cell *t);
+int t_wait_no_more_branches( struct cell *t, int extra);
 
 void get_cancel_reason(struct sip_msg *msg, int flags, str *reason);
 

modules/tm/tm.c

@@ -1590,7 +1590,7 @@ static int w_t_wait_no_more_branches(struct sip_msg* msg)
 		return -1;
 	}
 
-	if (t_wait_no_more_branches(t)<0)
+	if (t_wait_no_more_branches(t, 0)<0)
 		return -1;
 
 	return 1;