Only list extant explicit version

nvm.sh

@@ -130,7 +130,9 @@ nvm_ls() {
   fi
   # If it looks like an explicit version, don't do anything funny
   if [ `expr "$PATTERN" : "v[[:digit:]]*\.[[:digit:]]*\.[[:digit:]]*$"` != 0 ]; then
-    VERSIONS="$PATTERN"
+    if [ -d "$NVM_DIR/$PATTERN" ]; then
+      VERSIONS="$PATTERN"
+    fi
   else
     VERSIONS=`find "$NVM_DIR/" -maxdepth 1 -type d -name "$(nvm_format_version $PATTERN)*" -exec basename '{}' ';' \
       | sort -t. -u -k 1.2,1n -k 2,2n -k 3,3n | grep -v '^ *\.'`