Change
c2123ae380a372d5 exposed the fact that Perl_reg_temp_copy() didn't
reset SvMAGIC() to NULL after block copying the "parent" regexp. The analagous
problem with SvSTASH() was fixed with change
b9ad13acb338e137.
sizeof(regexp) - STRUCT_OFFSET(regexp, xpv_cur));
SvLEN_set(ret_x, 0);
SvSTASH_set(ret_x, NULL);
+ SvMAGIC_set(ret_x, NULL);
Newx(ret->offs, npar, regexp_paren_pair);
Copy(r->offs, ret->offs, npar, regexp_paren_pair);
if (r->substrs) {