manpages: check for ronn executable before doing anything

diff --git a/php/WP_CLI/InternalAssoc.php b/php/WP_CLI/InternalAssoc.php
index 6ceae0b..661d282 100644 (file)
--- a/php/WP_CLI/InternalAssoc.php
+++ b/php/WP_CLI/InternalAssoc.php
@@ -57,6 +57,10 @@ class InternalAssoc {
        }
 
        static function man( $args ) {
+               if ( '' === exec( 'which ronn' ) ) {
+                       WP_CLI::error( '`ronn` executable not found.' );
+               }
+
                $arg_copy = $args;
 
                $command = WP_CLI::$root;