D-Programming-Language/phobos — pull request #1792 by monarchdodra (2013-12-19 23:24:33+00:00)
Title: Fix Issue 11780 - RangeError in format for incomplete format specifier

I also had to rework the loop a tiny bit so as to preserve the fmt's integrity in case an exception is thrown (don't lose any previously not yet printed '%' character), as well as to have a coherent error message.