Ignore missing file when updating gems_list.txt.
Ignore missing file when updating gems_list.txt.

jsyeo/rubinius,kachick/rubinius,kachick/rubinius,kachick/rubinius,kachick/rubinius,jsyeo/rubinius,jsyeo/rubinius,jsyeo/rubinius,kachick/rubinius,kachick/rubinius,jsyeo/rubinius,jsyeo/rubinius,kachick/rubinius,kachick/rubinius,jsyeo/rubinius