Install python3-venv if it's not already installed on Linux, (#1317)

* Install python3.-venv if it's not already installed on Linux,

Author: jonsimantov

scripts/gha/install_prereqs_desktop.py

@@ -90,8 +90,8 @@ def main():
       if not ("gcc version 9." in gcc_ver.stderr or "gcc version 10." in gcc_ver.stderr):
         if (not utils.is_command_installed('gcc-10') or
             not utils.is_command_installed('g++-10')):
-          utils.run_command(['apt', 'install', '-y', 'gcc-10', 'g++-10'],
-                            as_root=True)
+          utils.run_command(['apt', 'install', '-y', 'gcc-10',
+                            'g++-10'], as_root=True)
         utils.run_command(['update-alternatives', '--install', '/usr/bin/gcc',
                            'gcc', '/usr/bin/gcc-10', '10'], as_root=True)
         utils.run_command(['update-alternatives', '--install', '/usr/bin/g++',
@@ -100,7 +100,12 @@ def main():
                            '/usr/bin/gcc-10'], as_root=True)
         utils.run_command(['update-alternatives', '--set', 'g++',
                            '/usr/bin/g++-10'], as_root=True)
-    
+
+    # On Linux, the python3-venv package is required.
+    if utils.is_linux_os():
+      if not utils.glob_exists("/usr/share/doc/python3.*-venv"):
+        utils.run_command(['apt', 'install', '-y', 'python3-venv'], as_root=True)
+
     # Install required python dependencies.
     # On Catalina, python2 in installed as default python.
     # Example command:

scripts/gha/utils.py

@@ -20,6 +20,7 @@
 """
 
 import distutils.spawn
+import glob
 import platform
 import shutil
 import subprocess
@@ -65,6 +66,11 @@ def is_command_installed(tool):
   return distutils.spawn.find_executable(tool)
 
 
+def glob_exists(glob_path):
+  """Check if any file/directory exists at a given path glob."""
+  return len(glob.glob(glob_path)) > 0
+
+
 def delete_directory(dir_path):
   """Recursively delete a valid directory"""
   if os.path.exists(dir_path):
@@ -260,4 +266,3 @@ def install_x86_support_libraries(gha_build=False):
       with open(os.devnull, "w") as devnull:
         subprocess.run(["dpkg", "-s"] + packages, stdout=devnull, stderr=subprocess.STDOUT,
                        check=True)
-