_ostree.py: Fix error handling to handle GLib.Error
diff --git a/buildstream/_ostree.py b/buildstream/_ostree.py
index d6e8c9e..a5029a6 100644
--- a/buildstream/_ostree.py
+++ b/buildstream/_ostree.py
@@ -153,16 +153,12 @@
 
         # complete repo transaction
         repo.commit_transaction(None)
-    except GLib.IOError as e:
+    except GLib.GError as e:
 
         # Reraise any error as a buildstream error
         repo.abort_transaction()
         raise OSTreeError(e.message) from e
 
-    except:
-        repo.abort_transaction()
-        raise
-
 
 # set_ref():
 #