Why would SVN not merge what diff shows?

I have a single working copy. BASE is r1901, HEAD is r1935. I don't want to update it yet,开发者_如何学Go but I want a specific change "from the future".

When I run svn diff -c 1921 . it show me all the changes. I could probably take the diff and apply it as a patch, but shouldn svn merge do exactly the same? But when I run svn merge -c 1921 . nothing happens.

svn propget svn:mergeinfo shows nothing.

Workaround: create branch from working copy.

Try to add a minus in front of 1921, such as:

svn merge -c -1921