When pattern is nil, enhance_with_matching_rule will not fail

[lzap]

This fixes the

NoMethodError: undefined method `match' for nil:NilClass

error with gettext/gettext_i18n_rails.

ManageIQ/manageiq#4774

[olleolleolle]

Only patterns that are present can match a rule name. This fix makes sense.

I get curious though: Why was that @rules element nil in its first position?

[lzap]

I put an inspect and it's full of nils strangely: [[nil, [], [], nil], [nil, [], [], nil], [nil, [], [], nil], [nil, [], [], nil], [nil, [], [], nil], [nil, [], [], nil]]

[hsbt]

Can you add new test about this change?