merge revision(s) 5d815542815fe8b939239750bba7f8f0b79c97d6: [Backport #18154]

	[Bug #18154] Fix memory leak in String#initialize

	String#initialize can leak memory when called on a string that is marked
	with STR_NOFREE because it does not unset the STR_NOFREE flag.
	---
	 string.c                 |  2 +-
	 test/ruby/test_string.rb | 10 ++++++++++
	 2 files changed, 11 insertions(+), 1 deletion(-)

1 files changed, 1 insertions, 1 deletions

diff --git a/string.c b/string.c
index ed101187ab..e8021ccd8d 100644
--- a/string.c
+++ b/string.c
@@ -1730,7 +1730,7 @@ rb_str_init(int argc, VALUE *argv, VALUE str)
                 const size_t osize = RSTRING(str)->as.heap.len + TERM_LEN(str);
                 char *new_ptr = ALLOC_N(char, (size_t)capa + termlen);
                 memcpy(new_ptr, old_ptr, osize < size ? osize : size);
-                FL_UNSET_RAW(str, STR_SHARED);
+                FL_UNSET_RAW(str, STR_SHARED|STR_NOFREE);
                 RSTRING(str)->as.heap.ptr = new_ptr;
 	    }
 	    else if (STR_HEAP_SIZE(str) != (size_t)capa + termlen) {