[MERGE] Rename on Windows is able to change filename case. (#77740)

[Vincent Ladeuil]

>>>>> "bialix" == Alexander Belchenko <bialix at ukr.net> writes:

    bialix> Aaron Bentley пишет:
    >> Alexander Belchenko wrote:
    >>> Aaron Bentley ?8H5B:
    >>>> Alexander Belchenko wrote:
    >>>>> Windows used case insensitive filesystem therefore rename (bzr mv) should care about special case
    >>>>> when only case is changed.
    >>>> bb:comment
    >>>> Could you please explain why we should avoid using fancy_rename in that
    >>>> special case.?
    >>> Because it simply did not work for this special case, but os.rename works just like a charm.
    >> 
    >> bb:approve
    >> 
    >> Well, this change is certainly better than what we have.  But it's not a
    >> complete fix:
    >> 
    >> 1. Windows may encounter case-sensitive filesystems over SMB or NFS.
    >> 2. Unix may encounter case-(insensitive + preserving) filesystems over
    >> SMB or NFS.
    >> 3. Unix and Windows may both encounter case-insensitive filesystems over
    >> ftp, sftp or bzr+ssh.
    >> 
    >> So while I'm willing to approve this because it likely fixes 95% of the
    >> cases, I'd rather see a fix to fancy_rename, because it would also fix
    >> ftp and sftp.

    bialix> I'm also like to see the complete fix, but we need some way
    bialix> to detect case-insensitivity first. In my spec:
    bialix> http://bazaar-vcs.org/CaseInsensitiveWorkingTreeSupport
    bialix> I assume that we can fast detect case sensitiveness at the moment when we open working tree.
    bialix> Unfortunately osutils is abstract layer, and checking case sensitiveness in each call of
    bialix> fancy_rename is overkill. Do you have better ideas?

Don't know if it's a better idea but:

I always thought we need write access to detect
case-insensitivity, but then I realized that bzr generally begin
working with a tree by checking some .bzr/*format (either for
branch or for repository).

So, once we get the content of a '.bzr/*format' file if we try
to get '.bzr*FORMAT' we know if we are using a case-sensitive
file system or not...