CMake: configure -system-pcre is ignored

I configure qtbase with

../configure -opensource -confirm-license -debug -developer-build [...] iconv -system-pcre -cmake

EDIT: I understand now that the "configure" script is not a first class citizen in the cmake build, and the -(system|qt)-whatever flags are not working yet. BUT in the summary of this configure run I see cmake outputting

using system pcre

so I assume it should do that.

However, as soon as I hit ninja, it starts building the bundled pcre2 for the bootstrap target. In file src/tools/bootstrap/CMakeLists.txt it looks like the 3rd party files are built unconditionally.

Is this on purpose? Is it done for static building of some sort? FYI my system provides also .a archives for this purpose:

$ rpm -ql pcre2-devel-static
/usr/lib64/libpcre2-16.a
/usr/lib64/libpcre2-32.a
/usr/lib64/libpcre2-8.a
/usr/lib64/libpcre2-posix.a