Da+rvocalic naming (Devangari)

I’m having trouble with the naming of a glyphs composed of Devanagari da and rvocalic. In the last release of Vesper Libre (June 3, 2015) the glyph name is d_rVocalicMatra-deva. If I try to use this name in 2.2.2 (827) Glyphs cannot build the feature code because the font does not contain d-deva (because there is no half-form version of da). Glyphs can build feature code if I use the name da_rVocalicMatra-deva. Is this a bug in Glyphs, or should I be using the name da_rVocalicMatra-deva?