Added test revealing a Fragmenter issue with collapsed annotations/fragments.
Added test revealing a Fragmenter issue with collapsed annotations/fragments.

abhaga/substance,michael/substance-1,TypesetIO/substance,andene/substance,substance/substance,substance/substance,michael/substance-1,stencila/substance,abhaga/substance,jacwright/substance,podviaznikov/substance,podviaznikov/substance,jacwright/substance,andene/substance,TypesetIO/substance