convert: fix test-convert-svn-* problems with mtime not changing The `svn commit` command does not detect changed files unless their mtime has changed. A quick succession of, for instance, `svn co ...; echo x >> y; svn ci` can thus lead to the change to y being ignored. Edited by pmezard to write in binary mode.

adding a
Now at: a.patch
applying b.patch
applying c.patch
Now at: c.patch
Now at: b.patch