diff --git a/ns3 b/ns3
index 360f594f6..d19047107 100755
--- a/ns3
+++ b/ns3
@@ -1255,6 +1255,9 @@ def main():
     if run_only or build_and_run:
         if target_to_run in ns3_programs:
             target_to_run = check_ambiguous_target("Run", target_to_run, ns3_programs)
+        elif ".py" in target_to_run and os.path.exists(target_to_run):
+            # We let python scripts pass to be able to run ./utils/python-unit-tests.py
+            pass
         else:
             raise Exception("Couldn't find the specified program: %s" % target_to_run)
 
diff --git a/utils/tests/gitlab-ci-gcc.yml b/utils/tests/gitlab-ci-gcc.yml
index e116be854..5c2df5a3a 100644
--- a/utils/tests/gitlab-ci-gcc.yml
+++ b/utils/tests/gitlab-ci-gcc.yml
@@ -19,6 +19,7 @@
     - apt-get --quiet install gcc g++ cmake ninja-build python python3 python-dev qtbase5-dev qtchooser qt5-qmake qtbase5-dev-tools openmpi-bin openmpi-common openmpi-doc libopenmpi-dev ccache flex bison libfl-dev sqlite3 libsqlite3-dev libxml2 libxml2-dev libgtk-3-dev libboost-all-dev gsl-bin libgsl0-dev ssh --yes
   variables:
     COMPILER: g++
+    ENABLE_MPI: --enable-mpi
 
 # GCC 8
 # weekly-build-gcc-8-debug:
diff --git a/utils/tests/gitlab-ci-pybindgen.yml b/utils/tests/gitlab-ci-pybindgen.yml
index 325d58ba2..2fd5ee7cd 100644
--- a/utils/tests/gitlab-ci-pybindgen.yml
+++ b/utils/tests/gitlab-ci-pybindgen.yml
@@ -1,24 +1,86 @@
-# pybindgen:
-#   stage: build
-#   image: archlinux
-#   only:
-#     variables:
-#       - $PYBINDGEN == "True"
-#   before_script:
-#     - pacman -Syu --noconfirm
-#     - pacman -Sy base-devel python ccache gsl gtk3 boost wget git --noconfirm
-#     - wget --no-check-certificate https://nat.onthewifi.net/ns3/castxml-git-0.3.4.r19.g8625aed-1-x86_64.pkg.tar
-#     - wget --no-check-certificate https://nat.onthewifi.net/ns3/python-pybindgen-0.21.0-1-x86_64.pkg.tar
-#     - wget --no-check-certificate https://nat.onthewifi.net/ns3/python-pygccxml-git-1.9.0.r104.g84be336-1-any.pkg.tar
-#     - pacman -U --noconfirm python-pygccxml-git-1.9.0.r104.g84be336-1-any.pkg.tar python-pybindgen-0.21.0-1-x86_64.pkg.tar castxml-git-0.3.4.r19.g8625aed-1-x86_64.pkg.tar
-#   script:
-#     - git clone https://github.com/afq984/python-cxxfilt.git
-#     - mv python-cxxfilt/cxxfilt bindings/python
-#     - CXX="g++" ./ns3 configure --disable-examples --disable-tests -d debug
-#     - ./ns3 --apiscan=$MODULE
-#     - git diff src > pybindgen_new.patch
-#   artifacts:
-#     paths:
-#       - pybindgen_new.patch
-#   timeout: 9h
+pybindgen-21.04:
+  image: ubuntu:21.04 # python 3.9
+  only:
+    variables:
+      - $RELEASE == "weekly"
+  before_script:
+    - apt-get update
+    - DEBIAN_FRONTEND=noninteractive apt-get install -y g++ cmake ninja-build ccache libgsl-dev libgtk-3-dev libboost-dev wget git python3 python3-pip
+    - pip install cxxfilt pygccxml pybindgen castxml
+  script:
+    - ./ns3 configure -G Ninja -- -DNS3_SCAN_PYTHON_BINDINGS=ON
+    - ./ns3 build apiscan-all
+    - ./ns3 configure --enable-python-bindings
+    - ./ns3 build
+    - ./ns3 run first.py
+    - ./ns3 run second.py
+    - ./ns3 run third.py
+    - ./ns3 run ./utils/python-unit-tests.py
+    - git diff src > pybindgen_new2104.patch
+  artifacts:
+    paths:
+      - pybindgen_new2104.patch
+  timeout: 9h
 
+
+pybindgen-20.04:
+  image: ubuntu:20.04 # python 3.8
+  only:
+    variables:
+      - $RELEASE == "manual"
+  before_script:
+    - apt-get update
+    - DEBIAN_FRONTEND=noninteractive apt-get install -y g++ cmake ninja-build ccache libgsl-dev libgtk-3-dev libboost-dev wget git python3 python3-pip
+    - pip install cxxfilt pygccxml pybindgen castxml
+  script:
+    - ./ns3 configure -G Ninja -- -DNS3_SCAN_PYTHON_BINDINGS=ON
+    - ./ns3 build apiscan-all
+    - ./ns3 configure --enable-python-bindings
+    - ./ns3 build
+    - ./ns3 run first.py
+    - ./ns3 run second.py
+    - ./ns3 run third.py
+    - ./ns3 run ./utils/python-unit-tests.py
+    - git diff src > pybindgen_new2004.patch
+  artifacts:
+    paths:
+      - pybindgen_new2004.patch
+  timeout: 9h
+
+pybindgen-18.04:
+  image: ubuntu:18.04 # python 3.6
+  only:
+    variables:
+      - $RELEASE == "manual"
+  before_script:
+    - apt-get update
+    - apt-get install -y software-properties-common
+    - add-apt-repository ppa:ubuntu-toolchain-r/test --yes
+    - apt-get update
+    - DEBIAN_FRONTEND=noninteractive apt-get install -y cmake ninja-build ccache libgsl-dev libgtk-3-dev libboost-dev wget git g++-9 gcc-9 python3 python3-pip llvm-dev libclang-dev
+    - update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-9 800 --slave /usr/bin/g++ g++ /usr/bin/g++-9
+    - pip3 install setuptools distro requests cxxfilt
+    - git clone https://gitlab.com/nsnam/bake.git
+    - export PATH=$PATH:`pwd`/bake/build/bin
+    - export PYTHONPATH=$PYTHONPATH:`pwd`/bake/build/lib
+    - export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:`pwd`/bake/build/lib
+    - cd bake
+    - mkdir -p build/lib
+    - ./bake.py configure -e pygccxml -e pybindgen
+    - ./bake.py download
+    - ./bake.py build
+    - cd ..
+  script:
+    - CXX=g++-9 ./ns3 configure -G Ninja -- -DNS3_SCAN_PYTHON_BINDINGS=ON
+    - ./ns3 build apiscan-all
+    - ./ns3 configure --enable-python-bindings
+    - ./ns3 build
+    - ./ns3 run first.py
+    - ./ns3 run second.py
+    - ./ns3 run third.py
+    - ./ns3 run ./utils/python-unit-tests.py
+    - git diff src > pybindgen_new1804.patch
+  artifacts:
+    paths:
+      - pybindgen_new1804.patch
+  timeout: 9h
diff --git a/utils/tests/gitlab-ci.yml b/utils/tests/gitlab-ci.yml
index cde0a987f..329e7a532 100644
--- a/utils/tests/gitlab-ci.yml
+++ b/utils/tests/gitlab-ci.yml
@@ -38,7 +38,7 @@ stages:
     - export CCACHE_BASEDIR=${PWD}
     - export CCACHE_DIR=${PWD}/$CCACHE_BASEDIR_VALUE
     - export MPI_CI=1
-    - CXX=$COMPILER ./ns3 configure -d $MODE -GNinja --enable-examples --enable-tests --enable-asserts --enable-mpi
+    - CXX=$COMPILER ./ns3 configure -d $MODE -GNinja --enable-examples --enable-tests --enable-asserts $ENABLE_MPI
     - ./ns3 build
     - if [ "$MODE" != "debug" ]; then ./test.py -n; fi
   cache:
@@ -103,37 +103,6 @@ per-commit-compile-optimized:
     - pacman -Syu --noconfirm
     - pacman -Sy base-devel python ccache gsl gtk3 boost ninja cmake --noconfirm
 
-# .cmake-build:
-#   stage: build
-#   script:
-#     - mkdir -p $CCACHE_BASEDIR_VALUE
-#     - export CCACHE_BASEDIR=${PWD}
-#     - export CCACHE_DIR=${PWD}/$CCACHE_BASEDIR_VALUE
-#     - ./ns3 configure -d $MODE -GNinja --enable-examples --enable-tests
-#     - ./ns3 build
-#     - ./test.py -n
-#   cache:
-#     paths:
-#       - $CCACHE_BASEDIR_VALUE/
-#   timeout: 9h
-#   variables:
-#     CCACHE_BASEDIR_VALUE: ns-3-ccache-storage
-    
-# per-commit-compile-release-cmake:
-#   extends: .cmake-build
-#   except:
-#     variables:
-#       - $PYBINDGEN == "True"
-#       - $RELEASE == "weekly"
-#       - $RELEASE == "daily"
-#   image: archlinux
-#   variables:
-#     COMPILER: g++
-#     MODE: release
-#   before_script:
-#     - pacman -Syu --noconfirm
-#     - pacman -Sy base-devel python ccache gsl gtk3 boost ninja cmake --noconfirm
-
 # Weekly jobs for other distribution and compilers
 include:
   - 'utils/tests/gitlab-ci-ubuntu.yml'
@@ -142,4 +111,4 @@ include:
   - 'utils/tests/gitlab-ci-clang.yml'
   - 'utils/tests/gitlab-ci-test.yml'
   - 'utils/tests/gitlab-ci-doc.yml'
-#  - 'utils/tests/gitlab-ci-pybindgen.yml'
+  - 'utils/tests/gitlab-ci-pybindgen.yml'