[Fix] `reinstall-packages`: Prevent install/link when no packages found

Fixes #1744.

nvm.sh

@@ -3339,9 +3339,14 @@ nvm() {
       LINKS="${NPMLIST##* //// }"
 
       nvm_echo "Reinstalling global packages from $VERSION..."
+      if [ -n "${INSTALLS}" ]; then
         nvm_echo "$INSTALLS" | command xargs npm install -g --quiet
+      else
+        nvm_echo "No installed global packages found..."
+      fi
 
       nvm_echo "Linking global packages from $VERSION..."
+      if [ -n "${LINKS}" ]; then
         (
           set -f; IFS='
 ' # necessary to turn off variable expansion except for newlines
@@ -3352,6 +3357,9 @@ nvm() {
             fi
           done
         )
+      else
+        nvm_echo "No linked global packages found..."
+      fi
     ;;
     "clear-cache" )
       command rm -f "$NVM_DIR/v*" "$(nvm_version_dir)" 2>/dev/null

test/slow/nvm reinstall-packages/setup_dir

@@ -3,6 +3,8 @@
 \. ../../../nvm.sh
 nvm install 0.10.28
 nvm install 0.10.29
+nvm install 4.7.1
+nvm install 4.7.2
 
 if [ -f ".nvmrc" ]; then
   mv .nvmrc .nvmrc.bak

test/slow/nvm reinstall-packages/teardown_dir

@@ -3,6 +3,8 @@
 \. ../../../nvm.sh
 nvm uninstall v0.10.28
 nvm uninstall v0.10.29
+nvm uninstall v4.7.1
+nvm uninstall v4.7.2
 
 rm -f .nvmrc
 

test/slow/nvm reinstall-packages/works with no installs

@@ -0,0 +1,18 @@
+#!/bin/sh
+
+die () { echo "$@" ; exit 1; }
+
+\. ../../../nvm.sh
+
+get_packages() {
+  npm list -g --depth=0 | \sed -e '1 d' -e 's/^.* \(.*\)@.*/\1/' -e '/^npm$/ d' | xargs
+}
+
+nvm use 4.7.2
+ORIGINAL_PACKAGES=$(get_packages)
+
+nvm reinstall-packages 4.7.1
+FINAL_PACKAGES=$(get_packages)
+
+[ -z "${ORIGINAL_PACKAGES}" ] || die "original packages were not empty: ${ORIGINAL_PACKAGES}"
+[ -z "${FINAL_PACKAGES}" ] || die "final packages were not empty: ${FINAL_PACKAGES}"