Migrate busses false detection

[Hildo Guillardi Júnior]

The new KiCad/Eschema have the feature/dialog migrate busses that detect different signal names at same bus.
I have a bus in my schematic witch I type several times the same label to be clear to identify the derivations (check image). The point is that the feature detect wrong this and ask my every time if I want to reassign the labels (and all options are the same).

Application: eeschema
Version: 5.1.0-unknown-2bcf38d~82~ubuntu16.04.1, release build
Libraries:
    wxWidgets 3.0.2
    libcurl/7.47.0 OpenSSL/1.0.2g zlib/1.2.8 libidn/1.32 librtmp/2.3
Platform: Linux 4.15.0-47-generic x86_64, 64 bit, Little endian, wxGTK
Build Info:
    wxWidgets: 3.0.2 (wchar_t,wx containers,compatible with 2.8) GTK+ 2.24
    Boost: 1.58.0
    OpenCASCADE Community Edition: 6.8.0
    Curl: 7.47.0
    Compiler: GCC 5.4.0 with C++ ABI 1009

Build settings:
    USE_WX_GRAPHICS_CONTEXT=OFF
    USE_WX_OVERLAY=OFF
    KICAD_SCRIPTING=ON
    KICAD_SCRIPTING_MODULES=ON
    KICAD_SCRIPTING_PYTHON3=OFF
    KICAD_SCRIPTING_WXPYTHON=ON
    KICAD_SCRIPTING_WXPYTHON_PHOENIX=OFF
    KICAD_SCRIPTING_ACTION_MENU=ON
    BUILD_GITHUB_PLUGIN=ON
    KICAD_USE_OCE=ON
    KICAD_USE_OCC=OFF
    KICAD_SPICE=ON

[Hildo Guillardi Júnior (hildogjr)]

The conflicting label should be tested by different names.

[Hildo Guillardi Júnior (hildogjr)]

Also in the new assigning should be replaced the name of each label instance connected to the bus, not just kept the last.

[Jon Evans (craftyjon)]

Fixed by https://git.launchpad.net/kicad/commit/?id=a92bb946128772558f121275066497d543436ce3

[Hildo Guillardi Júnior (hildogjr)]

Worked just fine!
Thinking: this test could be interesting to be called before the PCB synchronization and/or NET file export.

[Jon Evans (craftyjon)]

It should also be caught be ERC, we just added the dialog because this is a behavior change (so previously valid schematics are no longer valid)