"Having the soname be libpython3 is the whole point of the library": I think that the point of this library is "libpython3.so" filename, not soname. Everything should still work if libpython3.so had no soname at all.

(If somebody has installed unpatched Python 3.2, then ldconfig will create llibpython3.so symlink (e.g. /usr/lib/llibpython3.so) and linker will hardcode dependency on llibpython3.so in generated libraries/executables during linking against libpython3.so (e.g. when -lpython3 has been specified).)

(I will work on improved patch for -Wl,--no-as-needed.)