Before this change the first execute_async called by executemany()
removed "paramstyle" from the configuration map, leading to applying
default (==all) substitution rules for subsequent parameters.
Testing:
added a regression test (executemany() was totally untested)
Before this change the first execute_async called by executemany() removed "paramstyle" from the configuration map, leading to applying default (==all) substitution rules for subsequent parameters.
Testing: