[master] ecddfd74c Reapply "fetch: A beresp body cannot be BS_TAKEN"

[Nils Goroll]

commit ecddfd74c8a0e6ff310da9945f5bf49ad5523c18
Author: Dridi Boukelmoune <dridi.boukelmoune at gmail.com>
Date:   Fri Feb 14 16:45:48 2025 +0100

    Reapply "fetch: A beresp body cannot be BS_TAKEN"
    
    This reverts commit 8c4ae4f0e1c1990a48884b36e2b3e9acc8d162a1.
    
    I dispute the claim from the revert commit that bo->htc->body_status
    refers to the bereq, since this is managed by the V1F (HTTP/1 Fetch)
    code. What we fetch on the backend side is a beresp.

diff --git a/bin/varnishd/cache/cache_fetch.c b/bin/varnishd/cache/cache_fetch.c
index 196817512..2f67446b6 100644
--- a/bin/varnishd/cache/cache_fetch.c
+++ b/bin/varnishd/cache/cache_fetch.c
@@ -141,10 +141,11 @@ Bereq_Rollback(VRT_CTX)
 	bo = ctx->bo;
 	CHECK_OBJ_NOTNULL(bo, BUSYOBJ_MAGIC);
 
-	if (bo->htc != NULL &&
-	    bo->htc->body_status != BS_NONE &&
-	    bo->htc->body_status != BS_TAKEN)
-		bo->htc->doclose = SC_RESP_CLOSE;
+	if (bo->htc != NULL) {
+		assert(bo->htc->body_status != BS_TAKEN);
+		if (bo->htc->body_status != BS_NONE)
+			bo->htc->doclose = SC_RESP_CLOSE;
+	}
 
 	vbf_cleanup(bo);
 	VCL_TaskLeave(ctx, bo->privs);