Improve the 'parents' parsing for git and ignore any empty parts; also

react gracefully if we could not parse the parents for some weird reason.

NEWS.mdtext

@@ -37,6 +37,8 @@ or newer to properly run this version of Indefero!
   and only display this list if there are any branches available for all SCMs
 - If git's author name is not encoded in an UTF-8 compatible encoding, skip the author lookup,
   as we have no information what the author string is actually encoded in
+- Indefero no longer displays an empty parents paragraph in the commit view for root revisions of
+  a git repository
 
 ## Documentation
 

src/IDF/Scm/Git.php

@@ -646,7 +646,11 @@ class IDF_Scm_Git extends IDF_Scm
         $c['full_message'] = IDF_Commit::toUTF8($c['full_message']);
         $c['title'] = IDF_Commit::toUTF8($c['title']);
         if (isset($c['parents'])) {
-            $c['parents'] = explode(' ', trim($c['parents']));
+            $c['parents'] = preg_split('/ /', trim($c['parents']), -1, PREG_SPLIT_NO_EMPTY);
+        } else {
+            // this is actually an error state because we should _always_
+            // be able to parse the parents line with every git version
+            $c['parents'] = null;
         }
         $res[] = (object) $c;
         return $res;