Turn bereq.uncacheable read-only

This had the same effect as writing to beresp.uncacheble.

bin/varnishd/cache/cache_vrt_var.c

@@ -204,20 +204,6 @@ VRT_r_beresp_##field(VRT_CTX)				\
 
 /*--------------------------------------------------------------------*/
 
-void
-VRT_l_bereq_uncacheable(VRT_CTX, unsigned a)
-{
-	CHECK_OBJ_NOTNULL(ctx, VRT_CTX_MAGIC);
-	CHECK_OBJ_NOTNULL(ctx->bo, BUSYOBJ_MAGIC);
-
-	if (ctx->bo->do_pass && !a) {
-		VSLb(ctx->vsl, SLT_VCL_Error,
-		    "Ignoring attempt to reset bereq.uncacheable");
-	} else if (a) {
-		ctx->bo->do_pass = 1;
-	}
-}
-
 unsigned
 VRT_r_bereq_uncacheable(VRT_CTX)
 {

bin/varnishtest/tests/v00025.vtc

@@ -52,7 +52,6 @@ varnish v1 -arg "-i J.F.Nobody" -vcl+backend {
 	}
 
 	sub vcl_backend_fetch {
-		set bereq.uncacheable = false;
 		if (bereq.between_bytes_timeout < 10s) {
 			set bereq.http.quick = "please";
 		}

lib/libvcc/generate.py

@@ -360,17 +360,10 @@ sp_variables = [
 	('bereq.uncacheable',
 		'BOOL',
 		( 'backend', ),
-		( 'backend_fetch', ), """
-		Indicates whether the object requested from the backend is
-		going to be uncacheable - either because the request was an
-		explicit pass from the client side or a hit on an uncacheable
-		("hit for pass") object.
-
-		Setting this variable in vcl_backend_fetch makes the object
-		uncacheable.
-
-		Clearing the variable has no effect and will log the warning
-		"Ignoring attempt to reset bereq.uncacheable".
+		( ), """
+		Indicates whether this request is uncacheable due
+		to a pass in the client side or a hit on an existing
+		uncacheable object (aka hit-for-pass).
 		"""
 	),
 	('bereq.connect_timeout',