YCM现在改用install.py来安装了

见 https://github.com/Valloric/YouCompleteMe/blob/master/install.sh
python虽然没有bash普及。但是YCM本身也依赖python，所以还是可以假定每个用户都有python环境的。
为了摆脱WARNING，还是切换到`install.py`上来吧。

Author: spacewander

install.sh

@@ -34,14 +34,14 @@ export SHELL=$system_shell
 echo "Step4: compile YouCompleteMe"
 echo "It will take a long time, just be patient!"
 echo "If error,you need to compile it yourself"
-echo "cd $CURRENT_DIR/bundle/YouCompleteMe/ && bash -x install.sh --clang-completer"
+echo "cd $CURRENT_DIR/bundle/YouCompleteMe/ && python install.py --clang-completer"
 cd $CURRENT_DIR/bundle/YouCompleteMe/
 git submodule update --init --recursive
 if [ `which clang` ]   # check system clang
 then
-    bash -x install.sh --clang-completer --system-libclang   # use system clang
+    python install.py --clang-completer --system-libclang   # use system clang
 else
-    bash -x install.sh --clang-completer
+    python install.py --clang-completer
 fi
 
 echo "Install Done!"