The query planner now always prefers to implement a FROM-clause subquery using

a co-routine rather than flattening the subquery into the outer query.

FossilOrigin-Name: c9104b59c7ed360291f7f6fc8caae938e9840c77620d598e4096f78183bf807a

diff --cc manifest
index 3dc920122d1fd885ad162b2ddd4c92aa59216865,55d7ee5a1f3e689f51d1ff89e23452ebd9d4ea0d..4f79804d823f341a2f4033c41a2bead656554242
--- 1/manifest
--- 2/manifest
+++ b/manifest
@@@ -1,5 -1,5 +1,5 @@@
- C Improvements\sto\sa\scomment\sin\slempar.c.\s\sNo\scode\schanges.
- D 2017-10-02T02:32:12.306
 -C More\sdetails\sin\sthe\sheader\scomment\sof\spushDownWhereTerms().\s\sNo\schanges\sto\ncode.
 -D 2017-09-30T11:47:06.786
++C The\squery\splanner\snow\salways\sprefers\sto\simplement\sa\sFROM-clause\ssubquery\susing\na\sco-routine\srather\sthan\sflattening\sthe\ssubquery\sinto\sthe\souter\squery.
++D 2017-10-02T02:52:54.153
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  F Makefile.linux-gcc 7bc79876b875010e8c8f9502eb935ca92aa3c434
  F Makefile.msc 6033b51b6aea702ea059f6ab2d47b1d3cef648695f787247dd4fb395fe60673f
@@@ -1655,7 -1655,7 +1655,8 @@@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a9
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  F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
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  U drh
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diff --cc manifest.uuid
index 254a13150dfa7a1a3c196fba5f4314f4a437b684,8a76d04632d6bc3b35085fdc4731b710205f3b9f..9d275448b722cf21814e84d54b5406b9d6eabcf8
--- 1/manifest.uuid
--- 2/manifest.uuid
+++ b/manifest.uuid
@@@ -1,1 -1,1 +1,1 @@@
- 8000d230171fe53599fc6a916666f60f88f789e6c9c6c2869514c02d837d6fc8
 -928486231ff7cc0df17a5aa23a080a1b8720e168db5227a7dbd34861283ba689
++c9104b59c7ed360291f7f6fc8caae938e9840c77620d598e4096f78183bf807a