Fix for bugfix #12075: gamma node check for nan was always

checking red channel.

source/blender/nodes/intern/CMP_nodes/CMP_gamma.c

@@ -47,7 +47,7 @@ static void do_gamma(bNode *node, float *out, float *in, float *fac)
 	int i=0;
 	for(i=0; i<3; i++) {
 		/* check for negative to avoid nan's */
-		out[i] = (in[0] > 0.0f)? pow(in[i],fac[0]): in[0];
+		out[i] = (in[i] > 0.0f)? pow(in[i],fac[0]): in[i];
 	}
 	out[3] = in[3];
 }