You can get similar issues with Accurev... where they refer to one version
as being "stranded" or "overlapped"
2009/4/22 David Weintraub <qazwart_at_gmail.com>
> All this talk of -r<rev> vs. @<rev> reminds me of something the
> ClearCase people referred to as "Evil Twins".
>
> In ClearCase parlance, Evil Twins are two different files in two
> different revisions that share the same directory name and file name,
> but have no history in common. It looks like we're getting the same
> problem in Subversion.
>
> For example:
>
> Create a new repository and add a directory called foo with a file
> called foobar.txt. Commit your changes.
>
> Your repository looks like this:
>
> foo/foobar.txt
>
> Now create a directory called bar that is a sibling of foo and move
> the file foobar.txt to the bar directory and rename it barfoo.txt.
> Commit your changes.
>
> Your repository looks like this:
>
> foo/
> bar/barfoo.txt
>
> Now create a new file called foobar.txt under the foo directory.
> Commit your changes. Your repository will now look like this:
>
> foo/foobar.txt
> bar/barfoo.txt
>
> To our mortal eyes, we assume that foo/foobar.txt in Rev 1 of the
> repository is an ancestor of foo/foobar.txt in Rev 3 of the
> repository. However, this is not true, and Subversion knows this.
>
> If I do a log on foo/foobar.txt, I don't see that there was a file
> called foo/foobar.txt in Rev 1 of the repository, and doing a diff
> between the working copy and revision 1 doesn't work:
>
> $ svn diff -r1 foo/foobar.txt
> svn: Unable to find repository location for foobar.txt in revision 1.
>
> If, however, I do this:
>
> $ svn diff -r1 foo/foobar.txt_at_1
> ================================================
> --- foobar.txt (revision 1)
> +++ foobar.txt (working copy)
> - This is a file
> + This is a different file from before
>
> This works because I am now specifying not the file, but the file of
> the same name that was there at revision 1 of the repository.
>
> ClearCase administrators dreaded Evil Twins because they caused so
> much confusion with users. In fact, some sites went so far as to
> design triggers (hooks in Subversion) that would actually prevent you
> from creating Evil Twins. I believe this is why many version control
> systems to this day still do not deal with directory versioning.
>
> --
> David Weintraub
> qazwart_at_gmail.com
>
> ------------------------------------------------------
>
> http://subversion.tigris.org/ds/viewMessage.do?dsForumId=1065&dsMessageId=1862442
>
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>
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Received on 2009-04-22 18:34:16 CEST