[perl #124127] fix cloning arrays with unused elements

ce0d59fd changed arrays to use NULL instead of &PL_sv_undef for
unused elements, unfortunately it missed updating sv_dup_common()'s
initialization of unused elements, leaving them as &PL_sv_undef.

This resulted in modification of read only value errors at runtime.

(cherry picked from commit 902d16915db2735c3a41f15ef8d95cf300c31801)

1 files changed, 1 insertions, 1 deletions

diff --git a/sv.c b/sv.c
index af393bdeab..06db7d9b2c 100644
--- a/sv.c
+++ b/sv.c
@@ -12698,7 +12698,7 @@ S_sv_dup_common(pTHX_ const SV *const sstr, CLONE_PARAMS *const param)
 		    }
 		    items = AvMAX((const AV *)sstr) - AvFILLp((const AV *)sstr);
 		    while (items-- > 0) {
-			*dst_ary++ = &PL_sv_undef;
+			*dst_ary++ = NULL;
 		    }
 		}
 		else {