fixes #6301

fixes sdisability genes in general

Signed-off-by: Mloc <colmohici@gmail.com>

code/game/dna/genes/disabilities.dm

@@ -32,7 +32,7 @@
 		M.mutations.Add(mutation)
 	if(disability)
 		M.disabilities|=disability
-	if(mutation)
+	if(sdisability)
 		M.sdisabilities|=sdisability
 	if(activation_message)
 		M << "\red [activation_message]"
@@ -43,9 +43,9 @@
 	if(mutation && (mutation in M.mutations))
 		M.mutations.Remove(mutation)
 	if(disability)
-		M.disabilities-=disability
-	if(mutation)
-		M.sdisabilities-=sdisability
+		M.disabilities &= (~disability)
+	if(sdisability)
+		M.sdisabilities &= (~sdisability)
 	if(deactivation_message)
 		M << "\red [deactivation_message]"
 	else