Fix the transitive constraint logic error that can result in a null pointer

dereference.  Fix for ticket [e8d439c77685eca6].

FossilOrigin-Name: 228a7879870f8689e2f9b74fbef2ff93fab7b3c2

diff --cc manifest
index 2dd253cf309ad9e7dac3e84c4e38a4385a81da3a,a7d0cab6bb342dc0b848a6613d3f3e090e568a10..6abed8d72a7333568c5df6d8ee9c22360b7d0333
--- 1/manifest
--- 2/manifest
+++ b/manifest
@@@ -1,5 -1,5 +1,5 @@@
- C Prevent\sthe\sWhereLoop.rSetup\scost\sestimate\sfrom\sgoing\snegative\son\scomplex\nqueries.
- D 2016-06-26T04:06:28.081
 -C Add\stest\scases\sto\sthe\stransitive\sconstraint\sfix.
 -D 2016-07-01T19:48:43.147
++C Fix\sthe\stransitive\sconstraint\slogic\serror\sthat\scan\sresult\sin\sa\snull\spointer\ndereference.\s\sFix\sfor\sticket\s[e8d439c77685eca6].
++D 2016-07-01T20:12:39.149
  F Makefile.in bc2b4864a23a4a21c3e26d7b4350f51bab324d45
  F Makefile.linux-gcc 7bc79876b875010e8c8f9502eb935ca92aa3c434
  F Makefile.msc 50149765ef72f4e652b9a0f1f6462c4784bb9423
@@@ -1502,7 -1503,7 +1503,8 @@@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a9
  F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
  F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
  F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
- P 507014e4c7a70cd09410c89c8ed466c8edab39d2
- R ae55d782914cbf2db58c75f82f862316
 -P a33d23560959a127e37d8213dc00210cd4b05352
++P f81050859170c8708a1b296da8dd3ef0dd314a11 c952af89c22ddc31491f142b9511608a4c8f9737
+ R 9c182c2a1bd41d85d1ee54cc469d61e7
++T +closed c952af89c22ddc31491f142b9511608a4c8f9737
  U drh
- Z e21bca843071316b56d3c29d5bf9cc08
 -Z ef208312357a37b91bc1f6c737863420
++Z 6ff2c1fb4a902fab6eeb4b75477a29a3

diff --cc manifest.uuid
index ee49eb40ac05237c587fdfc17b4dbc2242b7eab8,7ba7a01a6121ada079aae2e235711983da335382..35505c7dd19a80a557e67dcb5d0e02cb262f9f02
--- 1/manifest.uuid
--- 2/manifest.uuid
+++ b/manifest.uuid
@@@ -1,1 -1,1 +1,1 @@@
- f81050859170c8708a1b296da8dd3ef0dd314a11
 -c952af89c22ddc31491f142b9511608a4c8f9737
++228a7879870f8689e2f9b74fbef2ff93fab7b3c2