Generate wrapper by default, fix shift for wrapper arguments

scripts/wrapper

@@ -25,11 +25,10 @@ wrap() {
 }
 
 symlink_binary() {
-  if [[ -f "$file_name" ]]; then
-    ln -fs "$file_name" "${rvm_bin_path}/${prefix}_${binary_name}"
-  else
-    $rvm_scripts_path/log "error" "Please run 'rvm wrapper $environment_identifier $binary_name' first."
-  fi
+  # Generate the default wrapper with the given binary name.
+  [[ ! -f "$file_name" ]] && wrap_binary
+  # Then symlink it into place.
+  ln -fs "$file_name" "${rvm_bin_path}/${prefix}_${binary_name}"
 }
 
 wrap_binary() {
@@ -56,7 +55,7 @@ fi
 ruby_string="$1"; shift
 
 prefix="$1"
-if [[ -z "$1" ]]; then shift; fi
+if [[ -n "$1" ]]; then shift; fi
 
 binaries="$(echo "$@" | sed -e 's/^[[:space:]]*//' -e 's/[[:space:]]*$//')"