Vcs: fix potential issue in VcsBaseEditor::getTitleId()
Vcs: fix potential issue in VcsBaseEditor::getTitleId()

In case the input list of filenames contains only empty item(s) then getTitleId()
fails to return a valid result.
It should return the workingDir or the revision.

Change-Id: I697826446037e4b1e9f94c4c0c558336f8d44237
Reviewed-by: Tobias Hunger <012f8d714267bccc9d4766fbeace9f175fcc70c4@theqtcompany.com>

kuba1/qtcreator,Distrotech/qtcreator,danimo/qt-creator,kuba1/qtcreator,Distrotech/qtcreator,kuba1/qtcreator,xianian/qt-creator,kuba1/qtcreator,martyone/sailfish-qtcreator,xianian/qt-creator,Distrotech/qtcreator,xianian/qt-creator,kuba1/qtcreator,Distrotech/qtcreator,danimo/qt-creator,danimo/qt-creator,kuba1/qtcreator,martyone/sailfish-qtcreator,xianian/qt-creator,Distrotech/qtcreator,martyone/sailfish-qtcreator,martyone/sailfish-qtcreator,Distrotech/qtcreator,martyone/sailfish-qtcreator,xianian/qt-creator,martyone/sailfish-qtcreator,martyone/sailfish-qtcreator,xianian/qt-creator,kuba1/qtcreator,martyone/sailfish-qtcreator,danimo/qt-creator,xianian/qt-creator,xianian/qt-creator,danimo/qt-creator,kuba1/qtcreator,danimo/qt-creator,kuba1/qtcreator,Distrotech/qtcreator,danimo/qt-creator,martyone/sailfish-qtcreator,xianian/qt-creator,danimo/qt-creator,danimo/qt-creator