Fix recent double free in S_parse_gv_stash_name()

RT #133977

My recent commit v5.29.9-29-g657ed7c1c1 moved all buffer freeing to
the end of the function, but missed removing one of the existing frees.

The problem was spotted by James E Keenan and diagnosed by Tony Cook; I just
added a test.

A simple reproducer is

my $def = defined *{"xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx'x"};

1 files changed, 0 insertions, 1 deletions

diff --git a/gv.c b/gv.c
index 61085f5c53..3b8759e88a 100644
--- a/gv.c
+++ b/gv.c
@@ -1665,7 +1665,6 @@ S_parse_gv_stash_name(pTHX_ HV **stash, GV **gv, const char **name,
                 gvp = (GV**)hv_fetch(*stash, key, is_utf8 ? -((I32)*len) : (I32)*len, add);
                 *gv = gvp ? *gvp : NULL;
                 if (!*gv || *gv == (const GV *)&PL_sv_undef) {
-                    Safefree(tmpfullbuf); /* free our tmpfullbuf if it was used */
                     goto notok;
                 }
                 /* here we know that *gv && *gv != &PL_sv_undef */