Merge bitcoin/bitcoin#35954: qa: Disable Qt's glib event dispatcher for GUI tests on OpenBSD

de2adc3 qa: Disable Qt's glib event dispatcher for GUI tests on OpenBSD (Hennadii Stepanov)

Pull request description:

  When `bitcoin-gui` is built against OpenBSD's system Qt packages (which have GLib support), shutdown emits "GLib-CRITICAL **: g_main_context_pop_thread_default: assertion 'stack != NULL' failed" messages on `stderr`, which the test framework treats as a failure.

  Set `QT_NO_GLIB=1` so Qt falls back to its poll-based event dispatcher, which avoids the GLib thread-default context entirely.

  Fixes bitcoin/bitcoin#35851.

  See the CI log here: https://github.com/hebasto/bitcoin-core-nightly/actions/runs/31510478034.

ACKs for top commit:
  maflcko:
    lgtm ACK de2adc3

Tree-SHA512: edc991c7a174bc304a4da0ca29ec97bcaece463289de3da5350a046f1133ce6d830c37d5188536ca2ce238d462e56de8f2167fdeeb1d1e5ecca38d60c8495cce

Author: fanquake

test/functional/test_framework/test_node.py

@@ -287,6 +287,17 @@ def start(self, extra_args=None, *, cwd=None, stdout=None, stderr=None, env=None
                 # does not provide. In particular, painting a QGroupBox can make Qt call
                 # addSubview: on an invalid native object (QTBUG-49686).
                 subp_env.setdefault("QT_STYLE_OVERRIDE", "fusion")
+            if platform.system() == "OpenBSD":
+                # The system Qt packages are built with GLib support, so Qt uses
+                # QEventDispatcherGlib, which pushes/pops the GLib thread-default
+                # main context in each thread. On OpenBSD the pop can run during
+                # thread exit after GLib's per-thread context stack has already
+                # been torn down, so shutdown emits messages like
+                #   (process:NNN): GLib-CRITICAL **: g_main_context_pop_thread_default:
+                #   assertion 'stack != NULL' failed
+                # on stderr, which the test framework treats as a failure.
+                # Fall back to Qt's poll-based event dispatcher instead.
+                subp_env.setdefault("QT_NO_GLIB", "1")
             subp_env.setdefault("LC_ALL", "nl_NL.UTF-8") # Set language to try to trigger translation bugs
             if sys.platform.startswith("linux") and "XDG_RUNTIME_DIR" not in subp_env:
                 # Qt prints warnings to stderr when XDG_RUNTIME_DIR is unset or has wrong