[master] a2c85e397 Polish 50780f307600fe14c367892bbd3e9c90535b85a2

[Nils Goroll]

commit a2c85e397e0a1bfba0478cd7c2e180ee1fc7d589
Author: Nils Goroll <nils.goroll at uplex.de>
Date:   Sat Jan 23 09:38:26 2021 +0100

    Polish 50780f307600fe14c367892bbd3e9c90535b85a2
    
    Do not overwrite an already latched errno.
    
    Note that it does not make any difference at the moment because we only
    ever use ENOMEM
    
    Ref #3502

diff --git a/bin/varnishd/cache/cache_esi_fetch.c b/bin/varnishd/cache/cache_esi_fetch.c
index 508d46e26..0624fefe1 100644
--- a/bin/varnishd/cache/cache_esi_fetch.c
+++ b/bin/varnishd/cache/cache_esi_fetch.c
@@ -120,10 +120,12 @@ vfp_esi_end(struct vfp_ctx *vc, struct vef_priv *vef,
 	CHECK_OBJ_NOTNULL(vc, VFP_CTX_MAGIC);
 	CHECK_OBJ_NOTNULL(vef, VEF_MAGIC);
 
-	if (retval == VFP_ERROR)
-		vef->error = errno ? errno : EINVAL;
-	else
+	if (retval == VFP_ERROR) {
+		if (vef->error == 0)
+			vef->error = errno ? errno : EINVAL;
+	} else {
 		assert(retval == VFP_END);
+	}
 
 	vsb = VEP_Finish(vef->vep);