Avoid showing new windows on Windows (#1929)

Signed-off-by: Bernat Gabor <bgabor8@bloomberg.net>

docs/changelog/1928.bugfix.rst

@@ -0,0 +1 @@
+Avoid spawning new windows when doing seed package upgrades in the background on Windows - by :user:`gaborbernat`.

src/virtualenv/seed/wheels/periodic_update.py

@@ -22,7 +22,7 @@ from six.moves.urllib.request import urlopen
 from virtualenv.app_data import AppDataDiskFolder
 from virtualenv.info import PY2
 from virtualenv.util.path import Path
-from virtualenv.util.subprocess import DETACHED_PROCESS, Popen
+from virtualenv.util.subprocess import CREATE_NO_WINDOW, Popen
 
 from ..wheels.embed import BUNDLE_SUPPORT
 from ..wheels.util import Wheel
@@ -186,7 +186,7 @@ def trigger_update(distribution, for_py_version, wheel, search_dirs, app_data, p
     pipe = None if debug else subprocess.PIPE
     kwargs = {"stdout": pipe, "stderr": pipe}
     if not debug and sys.platform == "win32":
-        kwargs["creationflags"] = DETACHED_PROCESS
+        kwargs["creationflags"] = CREATE_NO_WINDOW
     process = Popen(cmd, **kwargs)
     logging.info(
         "triggered periodic upgrade of %s%s (for python %s) via background process having PID %d",

src/virtualenv/util/subprocess/__init__.py

@@ -13,7 +13,7 @@ else:
     Popen = subprocess.Popen
 
 
-DETACHED_PROCESS = 0x00000008
+CREATE_NO_WINDOW = 0x80000000
 
 
 def run_cmd(cmd):
@@ -32,5 +32,5 @@ __all__ = (
     "subprocess",
     "Popen",
     "run_cmd",
-    "DETACHED_PROCESS",
+    "CREATE_NO_WINDOW",
 )

tests/unit/seed/wheels/test_periodic_update.py

@@ -29,7 +29,7 @@ from virtualenv.seed.wheels.periodic_update import (
     trigger_update,
 )
 from virtualenv.util.path import Path
-from virtualenv.util.subprocess import DETACHED_PROCESS
+from virtualenv.util.subprocess import CREATE_NO_WINDOW
 
 
 @pytest.fixture(autouse=True)
@@ -224,7 +224,7 @@ def test_trigger_update_no_debug(for_py_version, session_app_data, tmp_path, moc
     assert args == ([sys.executable, "-c", cmd],)
     expected = {"stdout": subprocess.PIPE, "stderr": subprocess.PIPE}
     if sys.platform == "win32":
-        expected["creationflags"] = DETACHED_PROCESS
+        expected["creationflags"] = CREATE_NO_WINDOW
     assert kwargs == expected
     assert process.communicate.call_count == 0