Crash when moving a bend LPE path with a complex path as paste path

[jazzynico]

Follow-up to bug #1478168 Bend LPE crash using a complex path as paste path (rev >= 14226).

Reproduced on Windows XP (32-bit), Inkscape trunk rev. 14648.
Not reproduced on Xubuntu 15.10 (64-bit), Inkscape trunk rev. 14651.

Steps to reproduce:
1. With pencil tool and very low smooth draw a path a bit complex
2. Copy to clipboard
3. Draw a star
4. Add bend LPE
5. Paste path from clipboard in path parameter -Paste Path-
6. Move the LPE object.
-> Crash with the following message:

--------
Warning: limit of 200 snap sources reached, some will be ignored
Warning: limit of 200 snap sources reached, some will be ignored
WARNING: Requested update while update in progress, counter = 3
WARNING: Requested update while update in progress, counter = 3
WARNING: Requested update while update in progress, counter = 3
** (inkscape.exe:3924): CRITICAL **: void Inkscape::SelTrans::grab(const Geom::Point&, gdouble, gdouble, bool, bool): assertion `!_grabbed' failed

[jazzynico (jazzynico)]

Test file from Bug #1478168.

[Alvin Penner (apenner)]

attached is a proposed patch for this bug. This corrects a logic error that could lead to accessing an illegal memory location. With this patch I am no longer able to reproduce the crash.

Any testing would be welcome, especially on Windows.

[Alvin Penner (apenner)]

- fix committed to rev 14659

- attempted to commit also to lib2geom, but failed:
http://inkscape.13.x6.nabble.com/unable-to-commit-to-lib2geom-or-maybe-just-confused-td4975577.html

[Alvin Penner (apenner)]

same fix committed to lib2geom, at:

https://github.com/inkscape/lib2geom

[Jabiertxof (jabiertxof)]

Great! Thanks Alvin.

[Qantas94Heavy (qantas94heavy)]

Fix released with Inkscape 0.92.