Bug when opening with single file.

[pintuxgu <pintuxgu hoevendesign com>]

Hi All,

I just tried right clicking on a file and then select "open with meld".
I saw my screen flicker momentarily and then meld was gone again.
Then I did some simple tests from the command line.

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This is what Meld 1.8.2 says to me:
meld ~/projects/c/TDatabase.cpp 
Traceback (most recent call last):
  File "/usr/bin/meld", line 173, in <module>
    main()
  File "/usr/bin/meld", line 165, in main
    new_window = app.parse_args(sys.argv[1:])
  File "/usr/lib/meld/meld/meldapp.py", line 169, in parse_args
    tab = open_paths(args, options.auto_compare, options.auto_merge)
  File "/usr/lib/meld/meld/meldwindow.py", line 791, in open_paths
    self._single_file_open(a)
  File "/usr/lib/meld/meld/meldwindow.py", line 781, in _single_file_open
    doc.set_location(path)
  File "/usr/lib/meld/meld/vcview.py", line 395, in set_location
    self.choose_vc(vc.get_vcs(os.path.abspath(location or ".")))
  File "/usr/lib/meld/meld/vc/__init__.py", line 86, in get_vcs
    max_depth = max(len(vc.root) for vc in vcs if vc.VC_ROOT_WALK)
ValueError: max() arg is an empty sequence

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With no argumenst it starts up normally:
paul dualcore:~$ meld


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paul dualcore:~$ ~/bin/meld-1.8.4/bin/meld projects/c/TDatabase.cpp 
Traceback (most recent call last):
  File "/home/paul/bin/meld-1.8.4/bin/meld", line 178, in <module>
    main()
  File "/home/paul/bin/meld-1.8.4/bin/meld", line 170, in main
    new_window = app.parse_args(sys.argv[1:])
  File "/home/paul/bin/meld-1.8.4/meld/meldapp.py", line 169, in parse_args
    tab = open_paths(args, options.auto_compare, options.auto_merge)
  File "/home/paul/bin/meld-1.8.4/meld/meldwindow.py", line 791, in open_paths
    self._single_file_open(a)
  File "/home/paul/bin/meld-1.8.4/meld/meldwindow.py", line 784, in _single_file_open
    doc.run_diff(path)
  File "/home/paul/bin/meld-1.8.4/meld/vcview.py", line 536, in run_diff
    comp_path = self.vc.get_path_for_repo_file(path)
  File "/home/paul/bin/meld-1.8.4/meld/vc/_vc.py", line 180, in get_path_for_repo_file
    raise NotImplementedError()
NotImplementedError

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3.11.0 starts up normally and compares the file to it's self and then it claims they are the same :)
paul dualcore:~$ ~/bin/meld-3.11.0/bin/meld ~/projects/c/TDatabase.cpp