Assertion failure in get_turns() caused by cart_intersect.

[awulkiew]

In cartesian relate strategy for collinear segments overlapping very tiny parts of each other the segments are detected as collinear(using ratios) but only one intersection point is generated. This is an unexpected state in get_turn_info collinear handler.

"POLYGON((-0.59322033898305082 -8.0508474576271194,-2.882352941176471 -7.7647058823529411,-2.8823529411764706 -7.7647058823529411,-3.7361111111111112 -6.5694444444444446,-3.4404145077720205 -5.766839378238342,-4.1864406779661012 -3.6779661016949152,-7.5252525252525251 -5.5858585858585865,-7.5862068965517242 -5.1896551724137936,-4.47887323943662 -2.859154929577465,-4.5789473684210531 -2.5789473684210527,-3 -1,-2.9310344827586206 -0.86206896551724144,-3.1764705882352944 -0.70588235294117663,-4.7401960784313726 -2.1274509803921577,-5.3255813953488369 -0.48837209302325502,-4.7872340425531918 0.31914893617021284,-5.8571428571428577 1.0000000000000007,-5.3255813953488369 -0.48837209302325502,-5.9473684210526319 -1.4210526315789465,-8 2,-7.7333333333333334 2.1939393939393939,-8.8294573643410867 2.891472868217055,-8.8556701030927822 3.061855670103093,-7.5999999999999996 3.6000000000000001,-7.7999999999999998 3.7999999999999998,-7.75 3.7916666666666665,-7.5471698113207548 3.6226415094339623,-7.3200000000000003 3.7200000000000002,-3.473684210526315 3.0789473684210527,-3.2549019607843133 3.2156862745098036,-2.9999999999999982 3.1428571428571423,-3.1733333333333325 3.2666666666666666,-2.9180327868852456 3.4262295081967209,-2.8723404255319145 3.1063829787234041,-2.1111111111111112 2.8888888888888888,-2.1428571428571428 2.8571428571428572,-1.8433734939759043 2.8072289156626509,-1.8396226415094346 2.8113207547169816,-1.6486486486486487 2.756756756756757,-1.76510067114094 2.8926174496644301,-0.53846153846153855 4.2307692307692308,1.8148148148148147 5.4074074074074074,1.588235294117647 2.2352941176470589,1.819672131147541 2.1967213114754101,2 4,2 2.1666666666666665,2.3538461538461544 2.1076923076923078,2 1.6875000000000004,2 -2,1.2173913043478262 -3.8260869565217392,1.7375886524822697 1.3758865248226959,1.5073170731707317 1.1024390243902444,1.1428571428571428 -4,-0.59322033898305082 -8.0508474576271194),(1.666666666666667 1.5999999999999988,1.5675675675675675 1.8378378378378377,1.4374999999999991 1.8750000000000002,1.0487804878048776 2.3414634146341466,0.46666666666666712 2.6060606060606055,0.086956521739131043 2.2608695652173911,1.4374999999999991 1.8750000000000002,1.666666666666667 1.5999999999999988))"
"POLYGON((-2.333333333333333 -8.6666666666666661,-4.3253012048192767 -8.168674698795181,-4.1194968553459113 -7.6100628930817606,-2.8823529411764706 -7.7647058823529411,-2.882352941176471 -7.7647058823529411,-2.263157894736842 -8.6315789473684212,-2.333333333333333 -8.6666666666666661))"

[awulkiew]

Fix: ​https://github.com/boostorg/geometry/commit/38389101829ed993523730ecedcd097fbf1ec70b