Fix argument of exists() function calls checking for autocommands. (#1165)

* Fix syntax of exists function calls checking for autocommands.

* Update version number in change log.

CHANGELOG.md

@@ -5,6 +5,7 @@
         - **.PATCH**: Pull Request Title (PR Author) [PR Number](Link to PR)
 -->
 #### 6.9
+- **.7**: Fix argument of `exists()` function calls checking for autocommands. (PhilRunninger) [#1165](https://github.com/preservim/nerdtree/pull/1165)
 - **.6**: Don't use silent when raising User events (PhilRunninger) [#1164](https://github.com/preservim/nerdtree/pull/1164)
 - **.5**: Fix highlight for file node.  (pirey) [#1157](https://github.com/preservim/nerdtree/pull/1157)
 - **.4**: Make sure symbolic links' flags are highlighted correctly.  (PhilRunninger) [#1156](https://github.com/preservim/nerdtree/pull/1156)

lib/nerdtree/creator.vim

@@ -28,7 +28,7 @@ endfunction
 
 " FUNCTION: s:Creator._broadcastInitEvent() {{{1
 function! s:Creator._broadcastInitEvent()
-    if exists('#NERDTreeInit')
+    if exists('#User#NERDTreeInit')
         doautocmd User NERDTreeInit
     endif
 endfunction

lib/nerdtree/nerdtree.vim

@@ -27,7 +27,7 @@ function! s:NERDTree.changeRoot(node)
     call self.render()
     call self.root.putCursorHere(0, 0)
 
-    if exists('#NERDTreeNewRoot')
+    if exists('#User#NERDTreeNewRoot')
         doautocmd User NERDTreeNewRoot
     endif
 endfunction