Qt Location maps tile cache crash

This was reported on the devel@lists.sailfishos.org mailing list (https://lists.sailfishos.org/pipermail/devel/2014-January/003099.html).

There is a crash in Qt Locations tile cache during map destruction.

For the first, I have a back button on a Map. If I start a flick and I press the back button while the Map is still flicking, it crashes. But it also crashes sometimes when the flick has finished so I can't simply test that flick is finished before doing the pagestack.pop():

Program received signal SIGSEGV, Segmentation fault.
QString::lastIndexOf (this=0x4, ch=..., from=-1, cs=Qt::CaseSensitive) at tools/qstring.cpp:2727
2727 tools/qstring.cpp: No such file or directory.
(gdb) backtrace
#0 QString::lastIndexOf (this=0x4, ch=..., from=-1, cs=Qt::CaseSensitive) at tools/qstring.cpp:2727
#1 0x40089bf0 in QGeoTileCache::~QGeoTileCache (this=0x400a750c, __in_chrg=<optimized out>) at maps/qgeotilecache.cpp:202
#2 0x4008a06c in QGeoTileCache::~QGeoTileCache (this=0x2ad71fd0, __in_chrg=<optimized out>) at maps/qgeotilecache.cpp:208
#3 0x4007ad98 in QGeoTiledMappingManagerEnginePrivate::~QGeoTiledMappingManagerEnginePrivate (this=0x2a2b6b10, __in_chrg=<optimized out>)
at maps/qgeotiledmappingmanagerengine.cpp:328
#4 0x4007aefc in QGeoTiledMappingManagerEngine::~QGeoTiledMappingManagerEngine (this=0x2a4d5a68, __in_chrg=<optimized out>) at maps/qgeotiledmappingmanagerengine.cpp:68
#5 0x47ca43b0 in QGeoTiledMappingManagerEngineNokia::~QGeoTiledMappingManagerEngineNokia (this=0x2a4d5a68, __in_chrg=<optimized out>)
at qgeotiledmappingmanagerengine_nokia.cpp:139
#6 0x47ca43fc in QGeoTiledMappingManagerEngineNokia::~QGeoTiledMappingManagerEngineNokia (this=0x2a4d5a68, __in_chrg=<optimized out>)
at qgeotiledmappingmanagerengine_nokia.cpp:139
#7 0x4007a210 in ~QGeoMappingManagerPrivate (this=0x2a84d6c0, __in_chrg=<optimized out>) at maps/qgeomappingmanager.cpp:190
#8 QGeoMappingManager::~QGeoMappingManager (this=0x2a51a010, __in_chrg=<optimized out>) at maps/qgeomappingmanager.cpp:96
#9 0x4007a244 in QGeoMappingManager::~QGeoMappingManager (this=0x2a51a010, __in_chrg=<optimized out>) at maps/qgeomappingmanager.cpp:97