Trying to fix MString assignments.

testing/zstring_test.cpp

@@ -1,5 +1,6 @@
 #include <iostream>
 #include "../ZString.h"
+#include "../MString.h"
 
 int main(int argc, char **argv) {
 
@@ -44,4 +45,12 @@ int main(int argc, char **argv) {
    std::cout << "find MX: " << testA.find("MX") << std::endl;
    std::cout << "unparsed: " << testA.unparsed() << std::endl;
 
+   std::string testb = "this is a string";
+   coreutils::ZString testc = testb;
+   std::cout << testc << std::endl;
+
+   coreutils::MString testd = "this is an mstring";
+   testc = testd;
+   std::cout << testc << std::endl;
+
 }