Make sure the new SimpleSAML_Configuration::getBasePath() complies with its...

Make sure the new SimpleSAML_Configuration::getBasePath() complies with its phpdoc, returning always at least a slash. Fix also the regex that's supposed to catch paths, as it still wants them to end with a slash.

lib/SimpleSAML/Configuration.php

@@ -487,16 +487,16 @@ class SimpleSAML_Configuration
         if (preg_match('#^https?://[^/]*(?:/(.+/?)?)?$#', $baseURL, $matches)) {
             // we have a full url, we need to strip the path
             if (!array_key_exists(1, $matches)) {
-                // root directory specified with an absolute URL
-                return '';
+                // absolute URL without path
+                return '/';
             }
-            return rtrim($matches[1], '/')."/";
+            return '/'.rtrim($matches[1], '/')."/";
         } elseif ($baseURL === '' || $baseURL === '/') {
             // root directory of site
-            return '';
-        } elseif (preg_match('#^/?([^/]?.*/)#D', $baseURL, $matches)) {
+            return '/';
+        } elseif (preg_match('#^/?((?:[^/\s]+/?)+)#', $baseURL, $matches)) {
             // local path only
-            return $matches[1];
+            return '/'.rtrim($matches[1], '/').'/';
         } else {
             /*
              * Invalid 'baseurlpath'. We cannot recover from this, so throw a critical exception and try to be graceful