make more tests green

changelog.md

@@ -83,6 +83,9 @@
 
 - ``nil`` for strings/seqs is finally gone. Instead the default value for
   these is ``"" / @[]``.
+- Accessing the binary zero terminator in Nim's native strings
+  is now invalid. Internally a Nim string still has the trailing zero for
+  zero-copy interoperability with ``cstring``.
 
 ### Tool changes