aggressive_conceal conflicting with headings 4 levels and deeper

[b0o]

g:org_aggressive_conceal causes headings with 4 stars to conceal down to 2 stars, presumably because it's thinking the outer two asterisks are bold markers and the inner two asterisks should be bolded.

I'm using the latest version of vim-orgmode (44faafa) and neovim v0.4.3.

:version
NVIM v0.4.3
Build type: Release
LuaJIT 2.0.5
Compilation: /usr/bin/cc -march=x86-64 -mtune=generic -O2 -pipe -fno-plt -O2 -DNDEBUG -DMIN_LOG_LEVEL=3 -Wall -
Wextra -pedantic -Wno-unused-parameter -Wstrict-prototypes -std=gnu99 -Wshadow -Wconversion -Wmissing-prototype
s -Wimplicit-fallthrough -Wvla -fstack-protector-strong -fdiagnostics-color=always -DINCLUDE_GENERATED_DECLARAT
IONS -D_GNU_SOURCE -DNVIM_MSGPACK_HAS_FLOAT32 -DNVIM_UNIBI_HAS_VAR_FROM -I/build/neovim/src/build/config -I/bui
ld/neovim/src/neovim-0.4.3/src -I/usr/include -I/build/neovim/src/build/src/nvim/auto -I/build/neovim/src/build
/include
Compiled by builduser

Features: +acl +iconv +tui