My installation of mercurial, tortoisehg, and hg-git on Ubuntu 20.04 and newer

install.sh

#!/bin/bash

TARGET_DIR=/opt/repos/third-parties
HG_GIT_VERSION=${1:-default}
HG_RELEASE_VERSION=${2:-5.5.2}
HG_REPO_VERSION=${3:-stable}
TORTOISEHG_VERSION=${4:-stable}

update() {
    # Update packages
    apt-get update
    apt-get -y dist-upgrade
}

prepare() {
    apt-get -y install \
    curl \
    gcc \
    make \
    python-is-python3 \
    python3 \
    python3-dev \
    python3-distutils \
    python3-docutils \
    python3-dulwich \
    python3-iniparse \
    python3-pip

    ## Ubuntu provides packages for PyQt5 and QScintilla, but there
    ## appears to be a bug in the versions shipped with Ubuntu 20.10
    ## that crashes TortoiseHG when viewing console logs. Until this bug
    ## is fixed, use pip to install QT5 dependencies
    # python3-pyqt5 \
    # python3-pyqt5.qsci \
    
    pip3 install PyQt5 QScintilla

    mkdir -p ${TARGET_DIR}
}

install_hg_release() {
    cd ${TARGET_DIR} \
    && curl "https://www.mercurial-scm.org/release/mercurial-${HG_RELEASE_VERSION}.tar.gz" -o mercurial.tar.gz \
    && tar xf mercurial.tar.gz \
    && rm -rf mercurial.tar.gz \
    && mv mercurial-* mercurial \
    && cd ${TARGET_DIR}/mercurial \
    && make -j $(nproc) build
}

install_hg_repo() {
    cd ${TARGET_DIR} \
    && ${TARGET_DIR}/mercurial/hg clone -u ${HG_REPO_VERSION} https://www.mercurial-scm.org/repo/hg \
    && cd ${TARGET_DIR}/hg \
    && make -j $(nproc) build install \
    && rm -rf ${TARGET_DIR}/mercurial
}

install_hg_git() {
    cd ${TARGET_DIR} \
    && hg clone https://foss.heptapod.net/mercurial/hg-git
}

install_tortoisehg() {
    cd ${TARGET_DIR} \
    && hg clone -u ${TORTOISEHG_VERSION} https://foss.heptapod.net/mercurial/tortoisehg/thg \
    && ln -fs ${TARGET_DIR}/thg/thg /usr/local/bin/thg
}

main() {
    set -xe

    update
    prepare
    install_hg_release
    install_hg_repo
    install_hg_git
    install_tortoisehg
}

main

I fixed a few problems (mostly related to file and folder permissions) and simplified the script to use pip and apt instead of building everything from source (also removed hg-git which I don't need, so it's not a drop-in analog for this original script).
https://gist.github.com/VioletGiraffe/166b62c4e170174976ee7691431c25e6