test-nointerrupt: make "sure" the handler "might" trigger (issue6558)

We are sure that the signal got sent in the right time frame, however, we still
have race, so either the code is actually buggy or we need some security to make
sure the signal get processed.

We might be affected by https://bugs.python.org/issue43406 ?

Differential Revision: https://phab.mercurial-scm.org/D11251

tests/test-nointerrupt.t

@@ -1,91 +1,94 b''
 #require no-windows no-rhg
 
 XXX-RHG this test hangs if `hg` is really `rhg`. This was hidden by the use of
 `alias hg=rhg` by run-tests.py. With such alias removed, this test is revealed
 buggy. This need to be resolved sooner than later.
 
 Dummy extension simulating unsafe long running command
   $ SYNC_FILE="$TESTTMP/sync-file"
   $ export SYNC_FILE
   $ DONE_FILE="$TESTTMP/done-file"
   $ export DONE_FILE
   $ 
   $ cat > wait_ext.py <<EOF
   > import os
   > import time
   > 
   > from mercurial.i18n import _
   > from mercurial import registrar
   > from mercurial import testing
   > 
   > cmdtable = {}
   > command = registrar.command(cmdtable)
   > 
   > @command(b'wait-signal', [], _(b'SYNC_FILE DONE_FILE'), norepo=True)
   > def sleep(ui, sync_file=b"$SYNC_FILE", done_file=b"$DONE_FILE", **opts):
   >     start = time.time()
   >     with ui.uninterruptible():
   >         testing.write_file(sync_file, b'%d' % os.getpid())
   >         testing.wait_file(done_file)
+  >         # make sure we get rescheduled and the signal get a chance to be handled
+  >         time.sleep(0.1)
   >         ui.warn(b"end of unsafe operation\n")
   >     ui.warn(b"%d second(s) passed\n" % int(time.time() - start))
   > EOF
 
   $ cat > send-signal.sh << EOF
   > #!/bin/sh
   > SIG=\$1
   > if [ -z "\$SIG" ]; then
   >    echo "send-signal.sh requires one argument" >&2
   >    exit 1
   > fi
   > "$RUNTESTDIR/testlib/wait-on-file" 10 "$SYNC_FILE" || exit 2
   > kill -s \$SIG \`cat "$SYNC_FILE"\`
+  > sleep 1
   > touch "$DONE_FILE"
   > EOF
 
 #if no-windows
   $ chmod +x send-signal.sh
 #endif
 
 Kludge to emulate timeout(1) which is not generally available.
 
 Set up repository
   $ hg init repo
   $ cd repo
   $ cat >> $HGRCPATH << EOF
   > [extensions]
   > wait_ext = $TESTTMP/wait_ext.py
   > EOF
 
 
 Test ctrl-c
   $ rm -f $SYNC_FILE $DONE_FILE
   $ sh -c "../send-signal.sh INT" &
   $ hg wait-signal
   interrupted!
   [255]
 
   $ cat >> $HGRCPATH << EOF
   > [experimental]
   > nointerrupt = yes
   > EOF
 
   $ rm -f $SYNC_FILE $DONE_FILE
   $ sh -c "../send-signal.sh INT" &
   $ hg wait-signal
   interrupted!
   [255]
 
   $ cat >> $HGRCPATH << EOF
   > [experimental]
   > nointerrupt-interactiveonly = False
   > EOF
 
   $ rm -f $SYNC_FILE $DONE_FILE
   $ sh -c "../send-signal.sh INT" &
   $ hg wait-signal
   shutting down cleanly
   press ^C again to terminate immediately (dangerous)
   end of unsafe operation
   interrupted!
   [255]