Fix a problem preventing the planner from identifying scans that visit at most

one row in cases where that property is guaranteed by a unique, not-null,
non-IPK column that is the leftmost in its table.

FossilOrigin-Name: 7fdb1e2ac2040dc47800a224d33a5c95d55200c480d46fedec1e97fb4f089ef7

diff --cc manifest
index b35a1be8bc7aa2f51f8590a19faca1d62ff7ef60,b3ae26712de6690a78461a9a46fce81f091b4e73..ace7d5414452859d2c0daab36abcdde7179ed460
--- 1/manifest
--- 2/manifest
+++ b/manifest
@@@ -1,5 -1,5 +1,5 @@@
- C Enhance\sthe\slog\smessages\sproduced\sin\ssome\scases\sif\sdatabase\scorruption\sis\nencountered\sby\san\sSQLITE_DEBUG\sbuild.
- D 2017-11-18T18:07:17.406
 -C Fix\sa\stypo\sin\sa\stest\sscript\son\sthis\sbranch.
 -D 2017-11-20T15:45:03.103
++C Fix\sa\sproblem\spreventing\sthe\splanner\sfrom\sidentifying\sscans\sthat\svisit\sat\smost\none\srow\sin\scases\swhere\sthat\sproperty\sis\sguaranteed\sby\sa\sunique,\snot-null,\nnon-IPK\scolumn\sthat\sis\sthe\sleftmost\sin\sits\stable.
++D 2017-11-20T15:46:10.484
  F Makefile.in b142eb20482922153ebc77b261cdfd0a560ed05a81e9f6d9a2b0e8192922a1d2
  F Makefile.linux-gcc 7bc79876b875010e8c8f9502eb935ca92aa3c434
  F Makefile.msc a55372a22454e742ba7c8f6edf05b83213ec01125166ad7dcee0567e2f7fc81b
@@@ -1677,8 -1677,7 +1677,8 @@@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a9
  F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
  F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
  F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
- P 723f1be3d4a905a6a16333f8ef3e1067dcd4944497b303033c49946fc37c780f 23a3128083834b5fc80adf45448f7dc65587c52761fb3c9483b80313b369406f
- R 05158c3570d45bd02cc2ba4cbb719bc9
- T +closed 23a3128083834b5fc80adf45448f7dc65587c52761fb3c9483b80313b369406f
 -P 299d7ca52fec32f04ffd2b8561dd4b839e891792162f8b00259368683436b02d
++P ee840a7669dd462af072625232ea4238198c9b94e1873f361c45f3b0985456f3 bff5dcfd2b29ee4834258914410a5dee69ec2727dd254053e3ebaf5090937694
+ R e3d55f8947932d938e221f1f7209d770
++T +closed bff5dcfd2b29ee4834258914410a5dee69ec2727dd254053e3ebaf5090937694
  U dan
- Z ce33cab931a12d704bb3e13109bc56c2
 -Z 5b68c810792c127ff29194bdbf236929
++Z 0d562170c07312a10559bcbda1122c53

diff --cc manifest.uuid
index f4e48d0118cbf7ae0cbc32ac7644b1cf816cb38c,f9d78fd1e6f379120662be2e00829a2649af5460..258ed7d3a36a438511be5808067c7d9882037c5a
--- 1/manifest.uuid
--- 2/manifest.uuid
+++ b/manifest.uuid
@@@ -1,1 -1,1 +1,1 @@@
- ee840a7669dd462af072625232ea4238198c9b94e1873f361c45f3b0985456f3
 -bff5dcfd2b29ee4834258914410a5dee69ec2727dd254053e3ebaf5090937694
++7fdb1e2ac2040dc47800a224d33a5c95d55200c480d46fedec1e97fb4f089ef7