Geary window does not open due to race condition: Bug #737811

Although prior fix for bug #737811 solved problem for some users,
apparently Geary still had an issue when upgrading a database with
new GLib Mutex implementation, which uses Linux's futexes whenever
available.  This solution gives the notifying thread a chance to
signal the waiter that its work is completed.

THANKS

@@ -34,6 +34,7 @@ Georges Basile Stavracas Neto <georges.stavracas@gmail.com>
 Philipp Nordhus <philipp@nhus.de>
 Andreas Obergrusberger <tradiaz@yahoo.de>
 Martin Olsson <martin@minimum.se>
+Mark Pariente <markpariente@gmail.com>
 Robert Park <rbpark@exolucere.ca>
 Mario Sanchez Prada <msanchez@igalia.com>
 Tiago Quelhas <tiagoq@gmail.com>

src/engine/util/util-synchronization.vala

@@ -64,10 +64,14 @@ public class SpinWaiter : BaseObject {
             int64 end_time = get_monotonic_time() + (actual_poll_msec * TimeSpan.MILLISECOND);
             if (!cond.wait_until(mutex, end_time)) {
                 // timeout passed, allow the callback to run
+                mutex.unlock();
                 if (!cb()) {
                     // PollService returned false, abort
+                    mutex.lock();
+                    
                     break;
                 }
+                mutex.lock();
             }
         }