Adding nvm_has_system_node

nvm.sh

@@ -28,6 +28,10 @@ nvm_download() {
   fi
 }
 
+nvm_has_system_node() {
+  [ $(nvm deactivate 2> /dev/null && command -v node) != '' ]
+}
+
 # Make zsh glob matching behave same as bash
 # This fixes the "zsh: no matches found" errors
 if nvm_has "unsetopt"; then

test/fast/Unit tests/nvm_has_system_node

@@ -0,0 +1,29 @@
+#!/bin/sh
+
+cleanup () {
+  rm ../../../v0.1.2/node
+  rmdir ../../../v0.1.2
+}
+die () { echo $@ ; exit 1; }
+
+. ../../../nvm.sh
+
+mkdir ../../../v0.1.2
+touch ../../../v0.1.2/node
+
+nvm use 0.1.2
+
+if command -v node; then
+  nvm_has_system_node
+else
+  ! nvm_has_system_node
+fi
+
+nvm deactivate /dev/null 2>&1
+
+if command -v node; then
+  nvm_has_system_node
+else
+  ! nvm_has_system_node
+fi
+