Comment 2 for bug 1700937

I've run git bisect on the https://github.com/mackyle/sqlite mirror of sqlite3 source code repository and spotted that the following commit fixes the issue :
https://github.com/mackyle/sqlite/commit/ce015fb42bbb6cafdbfc9b028c2ec0626a8f3217

This applies almost on top of sqlite 3.11.0 sources:

$ patch -p1 < /tmp/tmp.patch
patching file ext/rtree/rtree.c
Hunk #1 succeeded at 132 (offset -1 lines).
Hunk #2 succeeded at 506 (offset -113 lines).
Hunk #3 succeeded at 524 (offset -113 lines).
Hunk #4 succeeded at 541 (offset -113 lines).
Hunk #5 succeeded at 819 (offset -116 lines).
Hunk #6 succeeded at 858 (offset -116 lines).
Hunk #7 succeeded at 2961 (offset -220 lines).
Hunk #8 succeeded at 3002 (offset -220 lines).
Hunk #9 succeeded at 3055 (offset -227 lines).
Hunk #10 FAILED at 3490.
1 out of 10 hunks FAILED -- saving rejects to file ext/rtree/rtree.c.rej

The reject is
$ cat ext/rtree/rtree.c.rej
--- ext/rtree/rtree.c
+++ ext/rtree/rtree.c
@@ -3490,7 +3540,7 @@ static int rtreeInit(
   pRtree->zDb = (char *)&pRtree[1];
   pRtree->zName = &pRtree->zDb[nDb+1];
   pRtree->nDim = (u8)((argc-4)/2);
- pRtree->nDim2 = argc - 4;
+ pRtree->nDim2 = pRtree->nDim*2;
   pRtree->nBytesPerCell = 8 + pRtree->nDim2*4;
   pRtree->eCoordType = (u8)eCoordType;
   memcpy(pRtree->zDb, argv[1], nDb);

The nDim2 member doesn't exist in sqlite 3.11.0

I've attached the "clean" patch derived from this.