1. libpython3.so has soname "llibpython3.so" due to needless "l" in "-Wl,-hl$@".
2. libpython3.so is not linked against libpython$(LDVERSION).so when -Wl,--as-needed flag is used. -Wl,--as-needed flag is used by default in Gentoo due to major benefits.
From `info ld`:
`--as-needed'
`--no-as-needed'
This option affects ELF DT_NEEDED tags for dynamic libraries
mentioned on the command line after the `--as-needed' option.
Normally the linker will add a DT_NEEDED tag for each dynamic
library mentioned on the command line, regardless of whether the
library is actually needed or not. `--as-needed' causes a
DT_NEEDED tag to only be emitted for a library that satisfies an
undefined symbol reference from a regular object file or, if the
library is not found in the DT_NEEDED lists of other libraries
linked up to that point, an undefined symbol reference from
another dynamic library. `--no-as-needed' restores the default
behaviour.
I'm attaching the patch.