+ /* http://man7.org/linux/man-pages/man3/putenv.3.html
+ * int putenv(char *string);
+ * The string pointed to by string becomes part of the environment, so altering the
+ * string changes the environment.
+ * In other words, the memory pointed to by *string is used until
+ * a) another call to putenv() with the same e-var name
+ * b) the program exits
+ *
+ * Windows e-vars don't work that way, so let's not leak memory.
+ */