avoid nvm meltdown after set -eu

scripts/build_against_node.sh

 #!/usr/bin/env bash
 
-set -u -e -x
+if [[ ! -d ../.nvm ]]; then
+    git clone https://github.com/creationix/nvm.git ../.nvm
+fi
+source ../.nvm/nvm.sh
+nvm install $NODE_VERSION
+nvm use $NODE_VERSION
+
+set -u -e
 
 function publish() {
     if test "${COMMIT_MESSAGE#*'[publish binary]'}" != "$COMMIT_MESSAGE"; then
@@ -17,15 +24,6 @@ function publish() {
     fi
 }
 
-if [[ ! -d ../.nvm ]]; then
-    git clone https://github.com/creationix/nvm.git ../.nvm
-fi
-set +u
-source ../.nvm/nvm.sh
-nvm install $NODE_VERSION
-nvm use $NODE_VERSION
-set -u
-
 # test installing from source
 npm install --build-from-source
 node-pre-gyp package testpackage

scripts/build_against_node_webkit.sh

 #!/usr/bin/env bash
 
-set -u -e
 
 if [[ ! -d ../.nvm ]]; then
     git clone https://github.com/creationix/nvm.git ../.nvm
 fi
-set +u
 source ../.nvm/nvm.sh
 nvm install 0.10
-set -u
+
+set -u -e
 
 npm install nw-gyp -g