Crash in environment widget

Step to reproduce:
1) Create a new project
2) Go to "Project" mode and expand details of "Build environment" or "Run environment".
3) Click "Add", type "xxx" as a new variable name and "x" as its value. Ensure that "xxx" appears as the last item inside the table. If it's not the last give it another name so that it will be the last item.
4) Edit the new item's value once more. This time remove the whole contents and press enter - crash.

Call stack:

0 QBasicAtomicInt::ref qatomic_i386.h 120 0x804ce15
1 QString::QString qstring.h 729 0x2e7086e
2 Utils::Environment::key environment.cpp 270 0x2e6f406
3 Utils::EnvironmentModel::indexToVariable environmentmodel.cpp 106 0x2e72ea5
4 Utils::EnvironmentModel::data environmentmodel.cpp 150 0x2e730c8
5 QModelIndex::data qabstractitemmodel.h 398 0x7a4e64
6 QStyledItemDelegate::setEditorData qstyleditemdelegate.cpp 490 0x9d19e2
7 QAbstractItemView::dataChanged qabstractitemview.cpp 3169 0x91f25f
8 QAbstractItemView::qt_metacall moc_qabstractitemview.cpp 234 0x923bfc
9 QTableView::qt_metacall moc_qtableview.cpp 118 0x9556aa
10 QMetaObject::metacall qmetaobject.cpp 237 0x10c4214
11 QMetaObject::activate qobject.cpp 3278 0x10d71cd
12 QAbstractItemModel::dataChanged moc_qabstractitemmodel.cpp 148 0x112d43f
13 Utils::EnvironmentModel::setData environmentmodel.cpp 243 0x2e739a8
14 QStyledItemDelegate::setModelData qstyleditemdelegate.cpp 543 0x9d1e01
15 QAbstractItemView::commitData qabstractitemview.cpp 2770 0x91db2e
16 QAbstractItemView::qt_metacall moc_qabstractitemview.cpp 247 0x923e23
17 QTableView::qt_metacall moc_qtableview.cpp 118 0x9556aa
18 QMetaObject::metacall qmetaobject.cpp 237 0x10c4214
19 QMetaObject::activate qobject.cpp 3278 0x10d71cd
20 QAbstractItemDelegate::commitData moc_qabstractitemdelegate.cpp 102 0xab0236
21 QStyledItemDelegatePrivate::_q_commitDataAndCloseEditor qstyleditemdelegate.cpp 102 0x9d2b90
22 QStyledItemDelegate::qt_metacall moc_qstyleditemdelegate.cpp 73 0x9d2a69
23 QMetaObject::metacall qmetaobject.cpp 237 0x10c4214
24 QMetaCallEvent::placeMetaCall qobject.cpp 535 0x10d2333
25 QObject::event qobject.cpp 1217 0x10d33f9
26 QApplicationPrivate::notify_helper qapplication.cpp 4509 0x312f90
27 QApplication::notify qapplication.cpp 3909 0x31088f
28 QCoreApplication::notifyInternal qcoreapplication.cpp 787 0x10bcae6
29 QCoreApplication::sendEvent qcoreapplication.h 215 0x304d19
30 QCoreApplicationPrivate::sendPostedEvents qcoreapplication.cpp 1428 0x10bdb78
31 QCoreApplication::sendPostedEvents qcoreapplication.cpp 1321 0x10bd835
32 QCoreApplication::sendPostedEvents qcoreapplication.h 220 0x3d0c32
33 postEventSourceDispatch qeventdispatcher_glib.cpp 277 0x10f053c
34 g_main_context_dispatch /lib/i386-linux-gnu/libglib-2.0.so.0 0 0x155025f
35 ?? /lib/i386-linux-gnu/libglib-2.0.so.0 0 0x1550990
36 g_main_context_iteration /lib/i386-linux-gnu/libglib-2.0.so.0 0 0x1550c2a
37 QEventDispatcherGlib::processEvents qeventdispatcher_glib.cpp 422 0x10f0cee
38 QGuiEventDispatcherGlib::processEvents qguieventdispatcher_glib.cpp 204 0x3dc0c0
39 QEventLoop::processEvents qeventloop.cpp 149 0x10ba8a5
40 QEventLoop::exec qeventloop.cpp 201 0x10ba9e5
41 QCoreApplication::exec qcoreapplication.cpp 1064 0x10bd1cc
42 QApplication::exec qapplication.cpp 3783 0x3104a2
43 main main.cpp 398 0x805089b