[postgis-tickets] [PostGIS] #2172: Attempt to add antarctica main body twice fails second time

[PostGIS]

#2172: Attempt to add antarctica main body twice fails second time
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 Reporter:  strk      |       Owner:  strk         
     Type:  defect    |      Status:  new          
 Priority:  medium    |   Milestone:  PostGIS 2.0.3
Component:  topology  |     Version:  2.0.x        
 Keywords:            |  
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Comment(by strk):

 So, one of the "shaking" operations that happen in this case is that the
 line, which is a _closed_ line, gets rotated to start at the leftmost
 vertex, due to union, difference, intersection operations performed.

 After that we are left with _two_ edges to add, because the original first
 point was added as a node in the first insertion and now ends up splitting
 the geometry.

 This occurrence isn't supposed to result in a problem later, but it's
 worth pointing out that the effect of it is that of inserting two edges
 rather than a single one, so not the same as adding the identical thing
 twice.

 An effort could be made to reduce the shaking in these cases, but would
 still not fix the bug resulting from adding those two new edges (splitted
 on leftmost vertex).

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Ticket URL: <http://trac.osgeo.org/postgis/ticket/2172#comment:1>
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