--- a/mercurial/merge.py	Mon Nov 23 16:48:13 2020 -0800
+++ b/mercurial/merge.py	Mon Nov 23 23:08:58 2020 -0800
@@ -1912,7 +1912,7 @@
                         hint=_(b"use 'hg update' or check 'hg heads'"),
                     )
             if not force and (wc.files() or wc.deleted()):
-                raise error.Abort(
+                raise error.StateError(
                     _(b"uncommitted changes"),
                     hint=_(b"use 'hg status' to list changes"),
                 )