[TRUNK] exchange pos. stacking order crash (rev >= 14074)

not reproduced on Windows XP, Inkscape rev 14391
could you provide details of how you perform step 3,
3) Exchange positions of selected objects - stacking order

Reproduced with Inkscape 0.91+devel r14389 on OS X 10.7.5

@Alvin - in 'Align & Distribute', one of the new functions in 0.91 (see tooltips).

Based on tests with archived trunk builds:
- not reproduced with rev <= 14073,
- reproduced with rev >= 14076;
this crash is likely related to the merge of the SelContainer branch in rev 14074:
https://bazaar.launchpad.net/~inkscape.dev/inkscape/trunk/revision/14074

Program received signal EXC_BAD_ACCESS, Could not access memory.
Reason: 13 at address: 0x0000000000000000
0x000000010083cd01 in SPObject::isSiblingOf (this=0x6000000000000000, object=0x1126807f0) at sp-object.h:297
297 return this->parent && this->parent == object->parent;

Fixed in r14392.