It looks like according to the Unicode grapheme things, ‘degenerates’ do not have to be accounted for in supported the spec.
> Ignore degenerates. No special provisions are made to get marginally better behavior for degenerate cases that never occur in practice, such as an A followed by an Indic combining mark. So we don't *have* to support this case, but the spec makes it very clear that the grapheme separation rules are allowed to cover more cases which may not be covered by the rules laid out in http://unicode.org/reports/tr29/ #Default_Grapheme_Cluster_Table These degenerate cases are also not tested for in any of the Unicode grapheme spec tests they provide as well, so we are free to be smarter if we wish for this.
