rectangles sometimes turn into pentagons upon editing

[Alvin Penner]

The attached file consists of 11 rectangles.
They were created the same way using the rectangle tool.
Then I used Edit | Select All and then Path | Object to Path to convert them to paths.
Then use the Node tool to edit the nodes.
Some of them will remain rectangles or quadrilaterals, and some will develop a new side and become irregular pentagons. The breakage will occur when you try to edit the start/end point.
- the ones that will become pentagons will have a start point that is a little diamond instead of a large diamond.
- objects rect2585, 2573, 2579, 2587, 2591 will remain 4 sided upon editing
- objects rect2571, 2577, 2581, 2589, 2575, 2583 will become 5 sided if you try to edit the start/end point.

- this is a random process, the path coordinates after the initial move command are relative, but they appear to add up to zero as they should, so I see no way of determining a priori which ones will work and which won't.

- this problem did not exist in 0.46 from April 1, as far as I can tell

[Alvin Penner (apenner)]

the same issue affects the star/polygon tool.
attached is a file with 9 pentagons created with this tool
- of these pentagons, objects 2571, 2575, 2577, 2583 will remain pentagons if you edit them with the node tool
- objects 2573, 2579, 2581, 2585, 2587, will turn into hexagons if you edit the start/end point.

[Alvin Penner (apenner)]

forgot to say, running win32 Inkscape19754-080827.7z

the same issue affects the ellipse tool. attached is a file with 8 ellipses converted to paths. try to edit path 2571 using the node tool at the start/end. It will develop a new, unwanted, line segment.
The remaining 7 ellipses will remain ellipses (or, to be more precise, they will not develop new unwanted segments) if edited.

[prkos (prkos)]

duplicate of bug 257289?

[Alvin Penner (apenner)]

yes, I think so

just confirmed that the same issue can also happen when creating quadrilaterals using the Bezier node tool and manually closing the object by clicking on the start point, file attached, object 2589 will develop a new side if edited

[Alvin Penner (apenner)]

    on second thought, this is not the same as bug 257289. In 257289 extra nodes are being artificially created. In the present case the problem is not the presence of extra nodes, the problem is that sometimes an object is recognized as being closed while other times it is treated as open, and the distinction between the two is random.
   the start and end nodes are duplicated deliberately, for reasons that I do not understand. However, that is not necessarily a problem. The problem is that the algorithm is not consistently identifying which objects are closed and which are not closed. If you add up the cumulative x and y displacements on these rectangles they add up to precisely zero as they should, and yet the object is still not always identified as closed.