The retry added in the previous commit was unreachable - character 44 fits any cell, so the match
always succeeds and "nothing fits" arrives as a triclinic answer, not as no answer. Retry on a
triclinic answer instead, and only replace it when the second attempt finds a real class.
That makes the gate matter, and the angle tolerance is the wrong one to use for it. It says how far
a metric may sit from an ideal one and still be called it; the question here is whether the two
Niggli types are interchangeable at all, which they are only when the reduced beta is 90. Two
degrees off the boundary is a real type-1 cell, and presenting it in the obtuse setting promotes a
general triclinic lattice to C-centred monoclinic on residuals of about two degrees - which is what
happened to the triclinic case in the unit tests. Half a degree separates that from the crystal this
was found on, which sits 0.07 degrees from the boundary and matches on 0.006 to 0.135.
With the retry reachable and gated, that crystal's lattice comes out C-centred monoclinic from the
first pass at every geometry tried, including the one where its cell reduces to the acute setting
and the run used to merge in P1.
leonarski_f
c95951e872