Bring this transform function into sync with the policy established
by commit 3a382983d.
Also, fix it to make sure that what it drills down to is indeed a
hash, and not some other kind of Perl SV. Previously, the test
cases added here provoked crashes.
Because of the crash hazard, back-patch to 9.5 where this module
was introduced.
Discussion: https://postgr.es/m/28336.1528393969@sss.pgh.pa.us
The PostgreSQL contrib tree
---------------------------
This subtree contains porting tools, analysis utilities, and plug-in
features that are not part of the core PostgreSQL system, mainly
because they address a limited audience or are too experimental to be
part of the main source tree. This does not preclude their
usefulness.
User documentation for each module appears in the main SGML
documentation.
When building from the source distribution, these modules are not
built automatically, unless you build the "world" target. You can
also build and install them all by running "make all" and "make
install" in this directory; or to build and install just one selected
module, do the same in that module's subdirectory.
Some directories supply new user-defined functions, operators, or
types. To make use of one of these modules, after you have installed
the code you need to register the new SQL objects in the database
system by executing a CREATE EXTENSION command. In a fresh database,
you can simply do
CREATE EXTENSION module_name;
See the PostgreSQL documentation for more information about this
procedure.