compiled git master 2db3f76af8bdc5674a21ac6e44057a9d7fb31acf
Now trying to reply on a mail in inbox (Local Folders) crashes always.
Folder is set to "use default identity".

#0  0x00007f481f8328d7 in raise () from /lib64/libc.so.6
#1  0x00007f481f833caa in abort () from /lib64/libc.so.6
#2  0x00007f48204db68e in QMessageLogger::fatal(char const*, ...) const () from /usr/lib64/libQt5Core.so.5
#3  0x00007f48204d6cc1 in qt_assert_x(char const*, char const*, char const*, int) () from /usr/lib64/libQt5Core.so.5
#4  0x00007f481eccd154 in MailCommon::FolderSettings::fallBackIdentity (this=0x46ae700)
    at /home/KDE5/source/kde/pim/mailcommon/src/folder/foldersettings.cpp:324
#5  0x00007f481eccd3b2 in MailCommon::FolderSettings::identity (this=0x46ae700)
    at /home/KDE5/source/kde/pim/mailcommon/src/folder/foldersettings.cpp:348
#6  0x00007f481ec6deb3 in MailCommon::Util::folderIdentity (item=...)
    at /home/KDE5/source/kde/pim/mailcommon/src/util/mailutil.cpp:173
#7  0x00007f4825c0ee1d in CreateReplyMessageJob::start (this=0x97a7b90)
    at /home/KDE5/source/kde/pim/kmail/src/job/createreplymessagejob.cpp:64
#8  0x00007f4825b8ba51 in KMReplyCommand::execute (this=0x48292e0) at /home/KDE5/source/kde/pim/kmail/src/kmcommands.cpp:873
#9  0x00007f4825b87e6f in KMCommand::slotPostTransfer (this=0x48292e0, result=KMCommand::OK)
    at /home/KDE5/source/kde/pim/kmail/src/kmcommands.cpp:287
#10 0x00007f4825b99aae in QtPrivate::FunctorCall<QtPrivate::IndexesList<0>, QtPrivate::List<KMCommand::Result>, void, void (KMCommand::*)(KMCommand::Result)>::call (f=
    (void (KMCommand::*)(KMCommand * const, KMCommand::Result)) 0x7f4825b87e08 <KMCommand::slotPostTransfer(KMCommand::Result)>,
    o=0x48292e0, arg=0x7ffc636111b0) at /usr/include/qt5/QtCore/qobjectdefs_impl.h:136
#11 0x00007f4825b98ee5 in QtPrivate::FunctionPointer<void (KMCommand::*)(KMCommand::Result)>::call<QtPrivate::List<KMCommand::Result>, void> (f=
    (void (KMCommand::*)(KMCommand * const, KMCommand::Result)) 0x7f4825b87e08 <KMCommand::slotPostTransfer(KMCommand::Result)>,
    o=0x48292e0, arg=0x7ffc636111b0) at /usr/include/qt5/QtCore/qobjectdefs_impl.h:169
#12 0x00007f4825b9739f in QtPrivate::QSlotObject<void (KMCommand::*)(KMCommand::Result), QtPrivate::List<KMCommand::Result>, void>::impl (which=1, this_=0x110dec0, r=0x48292e0, a=0x7ffc636111b0, ret=0x0) at /usr/include/qt5/QtCore/qobject_impl.h:120