Fix utils::string::ssplit() to handle delimiter in the end of string

This closes #1743.

src/utils/string.cc

@@ -178,9 +178,14 @@ std::vector<std::string> ssplit(std::string str, char delimiter) {
     std::vector<std::string> internal;
     std::stringstream ss(str);  // Turn the string into a stream.
     std::string tok;
+    ssize_t n = str.length();
+    int i = 0;
 
     while (getline(ss, tok, delimiter)) {
-        internal.push_back(tok);
+        n -= tok.length();
+        if (i > 0) n--;
+        internal.push_back(n == 1 ? tok + delimiter : tok);
+        i++;
     }
 
     return internal;