[6.0] 78513e985 gc duplicate statement with no effect

[Dridi Boukelmoune]

commit 78513e9850f13a06987d551ed37b75eea2fda646
Author: Nils Goroll <nils.goroll at uplex.de>
Date:   Fri May 18 14:58:27 2018 +0200

    gc duplicate statement with no effect

diff --git a/bin/varnishd/cache/cache_gzip.c b/bin/varnishd/cache/cache_gzip.c
index 3694c0ad2..d5d256d56 100644
--- a/bin/varnishd/cache/cache_gzip.c
+++ b/bin/varnishd/cache/cache_gzip.c
@@ -620,7 +620,6 @@ vfp_testgunzip_pull(struct vfp_ctx *vc, struct vfp_entry *vfe, void *p,
 	CAST_OBJ_NOTNULL(vg, vfe->priv1, VGZ_MAGIC);
 	AN(p);
 	AN(lp);
-	CAST_OBJ_NOTNULL(vg, vfe->priv1, VGZ_MAGIC);
 	vp = VFP_Suck(vc, p, lp);
 	if (vp == VFP_ERROR)
 		return (vp);