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> # changes the prefix to be used for configure
> configure.pre_args-delete --prefix=${prefix}
> configure.args-append --prefix=${worksrcpath}/z3install

Don't do that.

The actual problem is here in the python-based configure script:
https://github.com/Z3Prover/z3/blob/z3-4.4.1/scripts/mk_util.py#L630

Instead of applying strange workarounds, patch this file to create the
directory at install time and not when parsing options.

> # todo: need to tell port to "cd ${worksrcpath}/build" before run "make"
> # currently, it "cd ${worksrcpath}" instead.
> build.cmd make -C build

build.dir ${worksrcpath}/build

However, then you also override the whole build phase with build {},
setting any build.* option is useless anyway. As you also override
destroot {}, no make command will be run at all. Is this intentional?

The patching of the Makefile in pre-build also seems unnecessary as you
could simply run make in the build phase.

Rainer