[COMMITTERS] pgsql: Fix detection of unfinished Unicode surrogate pair at end ofstr

Fix detection of unfinished Unicode surrogate pair at end of string.

The U&'...' and U&"..." syntaxes silently discarded a surrogate pair
start (that is, a code between U+D800 and U+DBFF) if it occurred at
the very end of the string.  This seems like an obvious oversight,
since we throw an error for every other invalid combination of surrogate
characters, including the very same situation in E'...' syntax.

This has been wrong since the pair processing was added (in 9.0),
so back-patch to all supported branches.

Discussion: https://postgr.es/m/19113.1482337898@sss.pgh.pa.us

Branch
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REL9_4_STABLE

Details
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http://git.postgresql.org/pg/commitdiff/d0f60e4cc5f20bf64ee12d740e52db2773a93c21

Modified Files
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src/backend/parser/scan.l | 8 ++++++++
1 file changed, 8 insertions(+)