[Gmsh] Problem trying to remove a surface with gmsh; bug?

[joel gervais]

Dear Christophe,
Thanks for this great software.Some .geo files I wrote many weeks ago lead to errors with the new version 3.0.5 of gmsh.It seems that something has changed between version 2.8.4 and 3.0.5 on windows 7 64 bits concerning the substract "-=" command.I've attached 2 pictures and the geo file (1 picture from gmsh 2.8.4 and the second from gmsh3.0.5)
The geo file builds a simple cylinder using an extrusion,and I try to remove the initial face to keep the rest of the cylinder's skin.
Regards
Joel
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