Add buffer subscriptions to repo's subscriptions

Closes #4570

spec/git-spec.coffee

@@ -259,6 +259,10 @@ describe "GitRepository", ->
       editor.getBuffer().emitter.emit 'did-change-path'
       expect(statusHandler.callCount).toBe 1
 
+    it "stops listening to the buffer when the repository is destroyed (regression)", ->
+      atom.project.getRepositories()[0].destroy()
+      expect(-> editor.save()).not.toThrow()
+
   describe "when a project is deserialized", ->
     [buffer, project2] = []
 

src/git-repository.coffee

@@ -412,6 +412,8 @@ class GitRepository
     bufferSubscriptions.add buffer.onDidDestroy =>
       bufferSubscriptions.dispose()
       @subscriptions.remove(bufferSubscriptions)
+    @subscriptions.add(bufferSubscriptions)
+    return
 
   # Subscribes to editor view event.
   checkoutHeadForEditor: (editor) ->