in unpack, () groups in scalar context were still returning a list,

resulting in garbage on the stack, which could manifest as a SEGV
(Bug 50256)

p4raw-id: //depot/perl@33239

1 files changed, 1 insertions, 0 deletions

diff --git a/pp_pack.c b/pp_pack.c
index 7bf1ce1746..98d4869f9c 100644
--- a/pp_pack.c
+++ b/pp_pack.c
@@ -1258,6 +1258,7 @@ S_unpack_rec(pTHX_ tempsym_t* symptr, const char *s, const char *strbeg, const c
 	    symptr->previous = &savsym;
             symptr->level++;
 	    PUTBACK;
+	    if (len && unpack_only_one) len = 1;
 	    while (len--) {
   	        symptr->patptr = savsym.grpbeg;
 		if (utf8) symptr->flags |=  FLAG_PARSE_UTF8;