UNC paths support broken on Windows98

[Alexander Belchenko]

Despite the fact I've added support for Windows 98 today I found the bug with UNC path handling.
Running any command om Windows 98 that use UNC path location as argument (e.g. branch or checkout command) and there is problem:

bzr arguments: [u'branch', u'\\\\HOST\\D\\Bazaar\\sandbox\\integration\\']
looking for plugins in D:\USER\python\bzr\bzr.dev\bzrlib\plugins
Plugin name __init__ already loaded
Plugin name __init__ already loaded
looking for plugins in C:/WINDOWS/Application Data/bazaar/2.0/plugins
encoding stdout as sys.stdout encoding 'cp866'
Traceback (most recent call last):
  File "D:\USER\python\bzr\bzr.dev\bzrlib\commands.py", line 650, in run_bzr_catch_errors
    return run_bzr(argv)
  File "D:\USER\python\bzr\bzr.dev\bzrlib\commands.py", line 612, in run_bzr
    ret = run(*run_argv)
  File "D:\USER\python\bzr\bzr.dev\bzrlib\commands.py", line 304, in run_argv_aliases
    return self.run(**all_cmd_args)
  File "D:\USER\python\bzr\bzr.dev\bzrlib\builtins.py", line 750, in run
    br_from = Branch.open(from_location)
  File "D:\USER\python\bzr\bzr.dev\bzrlib\branch.py", line 122, in open
    return control.open_branch(_unsupported)
  File "D:\USER\python\bzr\bzr.dev\bzrlib\bzrdir.py", line 1021, in open_branch
    format = BranchFormat.find_format(self)
  File "D:\USER\python\bzr\bzr.dev\bzrlib\branch.py", line 685, in find_format
    raise NotBranchError(path=transport.base)
NotBranchError: Not a branch: D:/HOST/D/Bazaar/sandbox/integration/.bzr/branch/

The problem itself in the python, in nt._getfullpathname function. This function used in implementation of os.path.abspath() that used by bzr during converting localpath to URL.
Illustration of problem:

D:\USER\python\bzr>python
Python 2.5 (r25:51908, Sep 19 2006, 09:52:17) [MSC v.1310 32 bit (Intel)] on win
32
Type "help", "copyright", "credits" or "license" for more information.
>>> import platform
>>> platform.platform()
'Windows-98-4.10.2222-A'
>>> import os
>>> os.path.abspath('\\\\HOST\path')
'\\\\HOST\\path'
>>> os.path.abspath('//HOST/path')
'D:\\HOST\\path'
>>>

I.e. on Windows98 abspath don't like forward slashes.

[Alexander Belchenko (bialix)]

Actually os.path.abspath is broken on Windows 98, because it rely on native Win32 API function GetFullPathName. And this function not only don't like '/' in UNC path but also don't support unicode filenames properly. So the best solution so far is to switch to alternate implementation of abspath on win98.
Excerpt from ntpath.py:

# Return an absolute path.
try:
    from nt import _getfullpathname

except ImportError: # not running on Windows - mock up something sensible
    def abspath(path):
        """Return the absolute version of a path."""
        if not isabs(path):
            path = join(os.getcwd(), path)
        return normpath(path)

else: # use native Windows method on Windows
    def abspath(path):
        """Return the absolute version of a path."""

        if path: # Empty path must return current working directory.
            try:
                path = _getfullpathname(path)
            except WindowsError:
                pass # Bad path - return unchanged.
        else:
            path = os.getcwd()
        return normpath(path)

The branch when ImportError occurs should be used on Windows 98 instead of native methods.