Tools: clamp empy to version 3

API and syntax hanges make 4 problematic

Tools/AP_Periph/wscript

@@ -7,7 +7,7 @@ import sys
 try:
     import em
 except ImportError:
-    print("you need to install empy with 'python -m pip install empy'")
+    print("you need to install empy with 'python -m pip install empy==3.3.4'")
     sys.exit(1)
 
 try:

Tools/ardupilotwaf/chibios.py

@@ -112,7 +112,7 @@ class upload_fw(Task.Task):
         and make sure to add it to your path during the installation. Once installed, run this
         command in Powershell or Command Prompt to install some packages:
         
-        pip.exe install empy pyserial
+        pip.exe install empy==3.3.4 pyserial
         ****************************************
         ****************************************
         """ % error_msg)

Tools/environment_install/install-prereqs-arch.sh

@@ -26,7 +26,7 @@ BASE_PKGS="base-devel ccache git gsfonts tk wget gcc"
 SITL_PKGS="python-pip python-setuptools python-wheel python-wxpython opencv python-numpy python-scipy"
 PX4_PKGS="lib32-glibc zip zlib ncurses"
 
-PYTHON_PKGS="future lxml pymavlink MAVProxy pexpect argparse matplotlib pyparsing geocoder pyserial empy dronecan"
+PYTHON_PKGS="future lxml pymavlink MAVProxy pexpect argparse matplotlib pyparsing geocoder pyserial empy==3.3.4 dronecan"
 
 # GNU Tools for ARM Embedded Processors
 # (see https://launchpad.net/gcc-arm-embedded/)

Tools/environment_install/install-prereqs-mac.sh

@@ -159,7 +159,7 @@ if [[ $DO_AP_STM_ENV -eq 1 ]]; then
     install_arm_none_eabi_toolchain
 fi
 
-PYTHON_PKGS="future lxml pymavlink MAVProxy pexpect geocoder flake8 empy dronecan"
+PYTHON_PKGS="future lxml pymavlink MAVProxy pexpect geocoder flake8 empy==3.3.4 dronecan"
 # add some Python packages required for commonly-used MAVProxy modules and hex file generation:
 if [[ $SKIP_AP_EXT_ENV -ne 1 ]]; then
     PYTHON_PKGS="$PYTHON_PKGS intelhex gnureadline"

Tools/environment_install/install-prereqs-ubuntu.sh

@@ -144,9 +144,9 @@ fi
 BASE_PKGS="build-essential ccache g++ gawk git make wget"
 if [ ${RELEASE_CODENAME} == 'bionic' ]; then
     # use fixed version for package that drop python2 support
-    PYTHON_PKGS="future lxml pymavlink MAVProxy pexpect flake8==3.7.9 requests==2.27.1 monotonic==1.6 geocoder empy configparser==4.0.2 click==7.1.2 decorator==4.4.2 dronecan"
+    PYTHON_PKGS="future lxml pymavlink MAVProxy pexpect flake8==3.7.9 requests==2.27.1 monotonic==1.6 geocoder empy==3.3.4 configparser==4.0.2 click==7.1.2 decorator==4.4.2 dronecan"
 else
-    PYTHON_PKGS="future lxml pymavlink MAVProxy pexpect flake8 geocoder empy dronecan"
+    PYTHON_PKGS="future lxml pymavlink MAVProxy pexpect flake8 geocoder empy==3.3.4 dronecan"
 fi
 
 # add some Python packages required for commonly-used MAVProxy modules and hex file generation:

Tools/environment_install/install-prereqs-windows-andAPMSource.ps1

@@ -19,7 +19,7 @@ Start-Process -wait -FilePath "C:\cygwin64\bin\bash" -ArgumentList "--login -i -
 Start-Process -wait -FilePath "C:\cygwin64\bin\bash" -ArgumentList "--login -i -c 'ln -sf /usr/bin/pip3.7 /usr/bin/pip'"
 
 Write-Output "Downloading extra Python packages (5/8)"
-Start-Process -wait -FilePath "C:\cygwin64\bin\bash" -ArgumentList "--login -i -c 'pip install empy pyserial pymavlink intelhex dronecan pexpect'"
+Start-Process -wait -FilePath "C:\cygwin64\bin\bash" -ArgumentList "--login -i -c 'pip install empy==3.3.4 pyserial pymavlink intelhex dronecan pexpect'"
 
 Write-Output "Downloading APM source (6/8)"
 Copy-Item "APM_install.sh" -Destination "C:\cygwin64\home"

Tools/environment_install/install-prereqs-windows.ps1

@@ -19,7 +19,7 @@ Start-Process -wait -FilePath "C:\cygwin64\bin\bash" -ArgumentList "--login -i -
 Start-Process -wait -FilePath "C:\cygwin64\bin\bash" -ArgumentList "--login -i -c 'ln -sf /usr/bin/pip3.7 /usr/bin/pip'"
 
 Write-Output "Downloading extra Python packages (5/7)"
-Start-Process -wait -FilePath "C:\cygwin64\bin\bash" -ArgumentList "--login -i -c 'pip install empy pyserial pymavlink intelhex dronecan pexpect'"
+Start-Process -wait -FilePath "C:\cygwin64\bin\bash" -ArgumentList "--login -i -c 'pip install empy==3.3.4 pyserial pymavlink intelhex dronecan pexpect'"
 
 Write-Output "Installing ARM GCC Compiler 10-2020-Q4-Major (6/7)"
 & $PSScriptRoot\gcc-arm-none-eabi-10-2020-q4-major-win32.exe /S /P /R

Tools/scripts/configure-ci.sh

@@ -101,5 +101,4 @@ python -m pip install --progress-bar off --user -U argparse pyserial pexpect fut
 python -m pip install --progress-bar off --user -U intelhex
 python -m pip install --progress-bar off --user -U numpy
 python -m pip install --progress-bar off --user -U edn_format
-python -m pip install --progress-bar off --user -U empy
+python -m pip install --progress-bar off --user -U empy==3.3.4
-