vcs.rb: search svn directory

* tool/vcs.rb (VCS::SVN#wcroot): search svn directory by
  traversing parent directories for old svn.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@49320 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

tool/vcs.rb

@@ -161,7 +161,13 @@ class VCS
         info = get_info
         @wcroot = info[/<wcroot-abspath>(.*)<\/wcroot-abspath>/, 1]
         unless @wcroot
-          STDERR.puts info.gsub(/^/, 'SVNINFO: ')
+          parent = File.realpath(@srcdir)
+          begin
+            parent = File.dirname(wkdir = parent)
+            if File.directory?(wkdir + "/.svn")
+              break @wcroot = wkdir
+            end
+          end until parent == wkdir
         end
       end
       @wcroot