[Base] Fix parsing composition strings when last name contains a colon

If the last species name in a composition string contained a colon, it would not
be parsed correctly.

src/base/stringUtils.cpp

@@ -147,12 +147,13 @@ compositionMap parseCompString(const std::string& ss,
             // this case, take the current substring as part of the key and look
             // to the right of the next colon for the corresponding value.
             // Otherwise, this is an invalid composition string.
-            std::string testname = ss.substr(valstart, stop-colon-1);
+            std::string testname = ss.substr(start, stop-colon-1);
             if (testname.find_first_of(" \n\t") != npos) {
                 // Space, tab, and newline are never allowed in names
                 throw;
             } else if (ss.substr(valstart, stop-colon-1).find(':') != npos) {
                 left = colon + 1;
+                stop = 0; // Force another iteration of this loop
                 continue;
             } else {
                 throw;

test/general/string_processing.cpp

@@ -33,6 +33,13 @@ TEST(parseCompString, name_with_colon)
     ASSERT_DOUBLE_EQ(1e-4, c["baz"]);
 }
 
+TEST(parseCompString, name_with_final_colon)
+{
+    compositionMap c = parseCompString("co:lons::1.0");
+    ASSERT_EQ((size_t) 1, c.size());
+    ASSERT_DOUBLE_EQ(1.0, c["co:lons:"]);
+}
+
 TEST(parseCompString, default_values)
 {
     std::vector<std::string> x = { "foo", "bar", "baz" };