[jira] [Commented] (SVN-4847) Automatic merge gets confused if merges are performed in parallel

["Stefan Sperling (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/SVN-4847?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17032852#comment-17032852 ] 

Stefan Sperling commented on SVN-4847:
--------------------------------------

See https://issues.apache.org/jira/secure/attachment/12992950/merge-interleave-3.sh.txt for a reproduction script by Daniel Dickison.

If the merge in Step 9 of that script is instead performed as follows, the merge completes without conflicts:
{code}
${SVN} merge -r0:HEAD ${URL}/trunk wcb
{code}




> Automatic merge gets confused if merges are performed in parallel
> -----------------------------------------------------------------
>
>                 Key: SVN-4847
>                 URL: https://issues.apache.org/jira/browse/SVN-4847
>             Project: Subversion
>          Issue Type: Bug
>          Components: libsvn_client
>    Affects Versions: all
>            Reporter: Stefan Sperling
>            Priority: Major
>         Attachments: merge-interleave-3.sh.txt
>
>
> The automatic merge heuristic will pick the wrong merge strategy if merges and commits are interleaved like this:
> 1. Create trunk and branch1
> 2. Commit an edit to file mu in trunk
> 3. Commit an edit to file iota in branch1
> 4. Merge trunk -> branch1
> 5. Merge branch1 -> trunk
> 6. Commit trunk
> 7. Commit branch1
> 8. Commit further edits to mu in trunk
> 9. Attempt to merge trunk into branch
> At step 9 Subversion performs a reintegrate merge which results in a spurious merge conflict. If a sync merge is forced instead the merge completes without conflicts. If there was a way to extend the heuristic to detect this case the
> merge conflict could be avoided.
> This problem was reported by Daniel Dickison and discussed in detail in the users@ list thread: "False conflict with interleaved merge commits":
> https://svn.haxx.se/users/archive-2020-02/0002.shtml
> https://svn.haxx.se/users/archive-2020-02/0004.shtml
> https://svn.haxx.se/users/archive-2020-02/0006.shtml
> https://svn.haxx.se/users/archive-2020-02/0007.shtml



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