Isolate AppImage smoke network and extraction state

docs/releasing.md

@@ -22,8 +22,10 @@ count. So a build reaches people only when you publish it, after testing it.
    the affected upload; it refuses ambiguous matches.
    The Linux build runs `scripts/check-appimage-launch.py` before upload. It
    starts the built x86_64 AppImage on an isolated Xvfb display, checks that
-   its bundled server answers, and checks that the server stops on exit. This
-   CI test does not test a physical display, FUSE mount or a headset.
+   its bundled server answers, and checks that the server stops on exit. The
+   check disables telemetry and update requests, and keeps extraction in its
+   temporary profile. This CI test does not test a physical display, FUSE mount
+   or a headset.
 
 2. Download the draft's installers and test them. An installed copy of the
    previous version won't offer the draft, so install it directly.

scripts/check-appimage-launch.py

@@ -45,13 +45,17 @@ def check(appimage):
     digest = hashlib.sha256(appimage.read_bytes()).hexdigest()
     with tempfile.TemporaryDirectory(prefix="frame-appimage-smoke-") as directory:
         profile = Path(directory)
+        (profile / "tmp").mkdir()
         env = dict(os.environ)
         env.update(
             APPIMAGE_EXTRACT_AND_RUN="1", ELECTRON_DISABLE_SANDBOX="1",
+            TMPDIR=str(profile / "tmp"),
             XDG_CONFIG_HOME=str(profile / "config"),
             XDG_CACHE_HOME=str(profile / "cache"),
             XDG_DATA_HOME=str(profile / "data"),
             FRAME_ALIAS="frame-control-appimage-smoke-no-headset",
+            FRAME_CONTROL_TELEMETRY="0", FRAME_CONTROL_NO_UPDATE_CHECK="1",
+            DO_NOT_TRACK="1",
         )
         output = profile / "app.log"
         port = None