Separate format_changelog

VCS::GITSVN#format_changelog generates previous format, similar to
svn-log, and VCS::GIT#format_changelog stores just git-log as-is
for now.

tool/vcs.rb

@@ -454,13 +454,35 @@ class VCS
     def export_changelog(url, from, to, path)
       range = [from, to].map do |rev|
         rev or next
+        if Integer === rev
           rev = cmd_read({'LANG' => 'C', 'LC_ALL' => 'C'},
                          %W"#{COMMAND} log -n1 --format=format:%H" <<
                          "--grep=^ *git-svn-id: .*@#{rev} ")
+        end
         rev unless rev.empty?
       end.join('^..')
       cmd_pipe({'TZ' => 'JST-9', 'LANG' => 'C', 'LC_ALL' => 'C'},
                %W"#{COMMAND} log --format=medium --no-notes --date=iso-local --topo-order #{range}", "rb") do |r|
+        format_changelog(r, path)
+      end
+    end
+
+    def format_changelog(r, path)
+      IO.copy_stream(r, path)
+    end
+
+    def commit(opts = {})
+      dryrun = opts.fetch(:dryrun) {$DEBUG} if opts
+      args = [COMMAND]
+      args << "-n" if dryrun
+      args << "push"
+      system(*args) or return false
+      true
+    end
+  end
+
+  class GITSVN < GIT
+    def format_changelog(r, path)
       open(path, 'w') do |w|
         sep = "-"*72
         w.puts sep
@@ -483,19 +505,7 @@ class VCS
         end
       end
     end
-    end
 
-    def commit(opts = {})
-      dryrun = opts.fetch(:dryrun) {$DEBUG} if opts
-      args = [COMMAND]
-      args << "-n" if dryrun
-      args << "push"
-      system(*args) or return false
-      true
-    end
-  end
-
-  class GITSVN < GIT
     def last_changed_revision
       rev = cmd_read(%W"#{COMMAND} svn info"+[STDERR=>[:child, :out]])[/^Last Changed Rev: (\d+)/, 1]
       com = cmd_read(%W"#{COMMAND} svn find-rev r#{rev}").chomp