My installation of tortoisehg on Ubuntu 20.04 and newer

install.sh

#!/bin/bash

TARGET_DIR=~/Downloads/repos/third-parties
TORTOISEHG_VERSION=${5:-stable}

prepare() {
    sudo apt-get -y update
    
    sudo apt-get -y install \
    curl \
    gcc \
    make \
    mercurial \
    python-is-python3 \
    python3 \
    python3-dev \
    python3-distutils \
    python3-docutils \
    python3-dulwich \
    python3-iniparse \
    python3-pip \
    libxcb-xinerama0
    
    pip3 install PyQt5 QScintilla mercurial

    mkdir -p ${TARGET_DIR}
}

install_tortoisehg() {
    echo 'Starting install_tortoisehg'

    cd ${TARGET_DIR}
    rm -rf thg || true
    rm /usr/local/bin/thg || true
    
    hg clone -u ${TORTOISEHG_VERSION} https://foss.heptapod.net/mercurial/tortoisehg/thg
    
    sudo mkdir /usr/local/bin/ || true
    sudo ln -fs ${TARGET_DIR}/thg/thg /usr/local/bin/thg
}

main() {
    set -xe

    prepare
    install_tortoisehg
}

main

sudo apt install tortoisehg