--- a/mercurial/cmdutil.py	Wed Mar 25 13:55:35 2015 +0900
+++ b/mercurial/cmdutil.py	Wed Mar 25 14:01:14 2015 -0700
@@ -2810,6 +2810,7 @@
         ## filling of the `names` mapping
         # walk dirstate to fill `names`
 
+        interactive = opts.get('interactive', False)
         wctx = repo[None]
         m = scmutil.match(wctx, pats, opts)
         if not m.always():
@@ -3031,7 +3032,10 @@
                             ui.note(_('saving current version of %s as %s\n') %
                                     (rel, bakname))
                             if not opts.get('dry_run'):
-                                util.rename(target, bakname)
+                                if interactive:
+                                    util.copyfile(target, bakname)
+                                else:
+                                    util.rename(target, bakname)
                     if ui.verbose or not exact:
                         if not isinstance(msg, basestring):
                             msg = msg(abs)
@@ -3044,7 +3048,6 @@
         if not opts.get('dry_run'):
             needdata = ('revert', 'add', 'undelete')
             _revertprefetch(repo, ctx, *[actions[name][0] for name in needdata])
-            interactive = opts.get('interactive', False)
             _performrevert(repo, parents, ctx, actions, interactive)
 
         # get the list of subrepos that must be reverted

--- a/tests/test-revert-interactive.t	Wed Mar 25 13:55:35 2015 +0900
+++ b/tests/test-revert-interactive.t	Wed Mar 25 14:01:14 2015 -0700
@@ -205,3 +205,53 @@
   4
   5
   f
+  $ hg st
+  M f
+  M folder1/g
+  R folder1/i
+  $ hg revert --interactive f << EOF
+  > y
+  > y
+  > n
+  > n
+  > EOF
+  diff -r 59dd6e4ab63a f
+  2 hunks, 2 lines changed
+  examine changes to 'f'? [Ynesfdaq?] y
+  
+  @@ -1,5 +1,6 @@
+  +a
+   1
+   2
+   3
+   4
+   5
+  record change 1/2 to 'f'? [Ynesfdaq?] y
+  
+  @@ -1,5 +2,6 @@
+   1
+   2
+   3
+   4
+   5
+  +b
+  record change 2/2 to 'f'? [Ynesfdaq?] n
+  
+  $ hg st
+  M f
+  M folder1/g
+  R folder1/i
+  ? f.orig
+  $ cat f
+  a
+  1
+  2
+  3
+  4
+  5
+  $ cat f.orig
+  1
+  2
+  3
+  4
+  5