[Gmsh] failure during extrude in 2.8.3

[Cian Wilson]

Hello,

The attached file is producing sporadic (about 1 in 5 times) errors with:

>> gmsh -3 region_id.geo
...
Info    : Linear search for (0.221823511110963, 0.09295446268021182, 1)
Error   : Could not find extruded vertex (0.221823511110963,
0.09295446268021182, 1)
... (repeated many times)
Error   : ------------------------------
Error   : Mesh generation error summary
Error   :     0 warnings
Error   :  4372 errors
Error   : Check the full log for details
Error   : ------------------------------

when using gmsh version 2.8.3.  It works fine with gmsh version 2.5.1.

The problem appears to occur at the line:
Extrude {0,0,0.01} {
  Surface{15,17,19,21}; Layers{1};
}

Thought I'd mention it here before reporting it as a bug in case it's
already fixed in the development version or there's something wrong in
my input.

Many thanks for the great tool and any thoughts on this!
Cian

-------------- next part --------------
Point(1) =  {0,   0.0, 0, 0.05};
Point(2) =  {0.5, 0.0, 0, 0.05};
Point(3) =  {0.5, 0.5, 0, 0.05};
Point(4) =  {0,   0.5, 0, 0.05};
Point(5) =  {0.5, 1,   0, 0.05};
Point(6) =  {0,   1,   0, 0.05};
Point(7) =  {0,   0.55, 0, 0.05};
Point(8) =  {0.5, 0.55, 0, 0.05};
Point(9) =  {0.5, 0.45, 0, 0.05};
Point(10) = {0,   0.45, 0, 0.05};
Line(1) = {1,10};
Line(2) = {10,4};
Line(3) = {4,7};
Line(4) = {7,6};
Line(5) = {6,5};
Line(6) = {5,8};
Line(7) = {8,3};
Line(8) = {3,9};
Line(9) = {9,2};
Line(10) = {2,1};
Line(11) = {10,9};
Line(12) = {3,4};
Line(13) = {7,8};
Line Loop(14) = {6,-13,4,5};
Plane Surface(15) = {14};
Line Loop(16) = {13,7,12,3};
Plane Surface(17) = {16};
Line Loop(18) = {2,-12,8,-11};
Plane Surface(19) = {18};
Line Loop(20) = {11,9,10,1};
Plane Surface(21) = {20};
Extrude {0,0,0.01} {
  Surface{15,17,19,21}; Layers{1};
}
Physical Surface(29) = {104};
Physical Surface(30) = {100,82,56,30};
Physical Surface(31) = {42};
Physical Surface(32) = {38,64,74,108};
Physical Surface(33) = {21,19,17,15};
Physical Surface(34) = {109,87,65,43};
Physical Volume(35) = {4};
Physical Volume(36) = {3};
Physical Volume(37) = {2};
Physical Volume(38) = {1};