Merge branch 'master' of github.com:github/atom

src/app/buffer.coffee

@@ -172,6 +172,7 @@ class Buffer
 
     @trigger 'before-save'
     fs.write path, @getText()
+    @file?.updateMd5()
     @modified = false
     @setPath(path)
     @trigger 'after-save'

src/app/file.coffee

@@ -5,7 +5,11 @@ _ = require 'underscore'
 
 module.exports =
 class File
+  path: null
+  md5: null
+
   constructor: (@path) ->
+    @updateMd5()
 
   getPath: ->
     @path
@@ -13,6 +17,9 @@ class File
   getName: ->
     fs.base(@path)
 
+  updateMd5: ->
+    @md5 = fs.md5ForPath(@path)
+
   afterSubscribe: ->
     @subscribeToNativeChangeEvents() if @subscriptionCount() == 1
 
@@ -21,7 +28,10 @@ class File
 
   subscribeToNativeChangeEvents: ->
     @watchId = $native.watchPath @path, (eventTypes) =>
-      @trigger 'contents-change' if eventTypes.modified?
+      newMd5 = fs.md5ForPath(@getPath())
+      if eventTypes.modified? and newMd5 != @md5
+        @md5 = newMd5
+        @trigger 'contents-change'
 
   unsubscribeFromNativeChangeEvents: ->
     $native.unwatchPath(@path, @watchId)