Issue:
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When a varchar column is used to fill the record in an
internal temporary table, the length of the string stored
in the column is not taken into account. Instead the
default length of packed data is used to copy with memmove.
This will cause valgrind issues since some bytes are
uninitialized.

SOLUTION:
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The solution is to take into account the length of the
string stored in the column while filling the record.

This fix is a backport of BUG#13389854.