backport.pl: Consistently use $SVN as a string.
backport.pl: Consistently use $SVN as a string.

Found by: breser

* tools/dist/backport.pl
  (vote): Introduce a tempfile.
  (*): Use the one-argument form of system() to call $SVN.

git-svn-id: f8a4e5e023278da1e04e203c7fe051e3c4285d88@1500937 13f79535-47bb-0310-9956-ffa450edef68

YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion