Bug 1712133: Remove build VIRTUALENV_NAME customization r=glandium

This was originally set up so that tests wouldn't "create a new
`virtualenv` for no reason." However, virtual environments now will have
different packages installed, and therefore the separation is necessary.

So, for the virtual environment used for builds (regular or for tests):
* We want it to be able to reuse the build venv, if it already exists.
* We don't want to pollute a `pytest` virtualenv with build-specific
  packages.

Differential Revision: https://phabricator.services.mozilla.com/D115641

build/moz.configure/init.configure

@@ -218,15 +218,8 @@ shell = help_shell | shell
 
 option(env="PYTHON3", nargs=1, help="Python 3 interpreter (3.6 or later)")
 
-option(
-    env="VIRTUALENV_NAME",
-    nargs=1,
-    default="common",
-    help="Name of the in-objdir virtualenv",
-)
 
-
-@depends("PYTHON3", "VIRTUALENV_NAME", check_build_environment, mozconfig, "--help")
+@depends("PYTHON3", check_build_environment, mozconfig, "--help")
 @imports(_from="__builtin__", _import="Exception")
 @imports("os")
 @imports("sys")
@@ -238,7 +231,7 @@ option(
 @imports(_from="mozbuild.pythonutil", _import="find_python3_executable")
 @imports(_from="mozbuild.pythonutil", _import="python_executable_version")
 @imports(_from="six", _import="ensure_text")
-def virtualenv_python3(env_python, virtualenv_name, build_env, mozconfig, help):
+def virtualenv_python3(env_python, build_env, mozconfig, help):
     # Avoid re-executing python when running configure --help.
     if help:
         return
@@ -256,7 +249,6 @@ def virtualenv_python3(env_python, virtualenv_name, build_env, mozconfig, help):
     log.debug("python3: sys.executable: %r" % sys.executable)
 
     python = env_python[0] if env_python else None
-    virtualenv_name = virtualenv_name[0]
 
     # Did our python come from mozconfig? Overrides environment setting.
     # Ideally we'd rely on the mozconfig injection from mozconfig_options,
@@ -292,7 +284,7 @@ def virtualenv_python3(env_python, virtualenv_name, build_env, mozconfig, help):
     with LineIO(lambda l: log.info(l), "replace") as out:
         manager = VirtualenvManager(
             topsrcdir,
-            os.path.join(virtualenvs_root, virtualenv_name),
+            os.path.join(virtualenvs_root, "common"),
             out,
             os.path.join(topsrcdir, "build", "build_virtualenv_packages.txt"),
         )

python/mozbuild/mozbuild/test/configure/common.py

@@ -305,7 +305,6 @@ class BaseConfigureTest(unittest.TestCase):
                 environ,
                 OLD_CONFIGURE=os.path.join(topsrcdir, "old-configure"),
                 MOZCONFIG=mozconfig_path,
-                VIRTUALENV_NAME="python-test",
             )
 
             paths = dict(paths)

python/mozbuild/mozbuild/test/configure/test_toolkit_moz_configure.py

@@ -29,9 +29,7 @@ class TestToolkitMozConfigure(BaseConfigureTest):
             del sandbox._implied_options[:]
             result = sandbox._value_for(sandbox["all_configure_options"])
             shell = mozpath.abspath("/bin/sh")
-            return result.replace("CONFIG_SHELL=%s " % shell, "").replace(
-                "VIRTUALENV_NAME=python-test ", ""
-            )
+            return result.replace("CONFIG_SHELL=%s " % shell, "")
 
         self.assertEquals(
             "--enable-application=browser",