Inkscape trunk: 'Construct Grid' LPE broken (rev >= 12348)

[su_v]

Original report:
================
Steps to reproduce:
1) launch current trunk (default prefs, default new doc)
2) draw a path with three cusp nodes (forming a right angle)
3) apply path effect 'Construct Grid'

Expected result:
an evenly spaced 5x5 grid (default initial setting)

Actual result:
Evenly arranged radial lines, focus in the opposite corner of the expected grid, extending towards the edges of the bounding box of the (expected) grid.

First noticed with r13272 on OS X 10.7.5, based on tests with archived builds:
- not reproduced with rev <= 13245,
- reproduced with rev >= 13248;
this regression is likely related to the 2geom update in rev 13246-13248:
<http://bazaar.launchpad.net/~inkscape.dev/inkscape/trunk/changes/13248>

Update:
=======
Johan committed a temporary fix in revision r13273:
"temporary fix for bug in 2geom, the bug manifests itself in LPE Construct grid"
<http://bazaar.launchpad.net/~inkscape.dev/inkscape/trunk/revision/13273>

Proper fix still pending (lib2geom).

[Krzysztof Kosinski (tweenk)]

This no longer happens as of r14299, even though 2Geom sources are fully synced.