# HG changeset patch
# User Yuya Nishihara <yuya@tcha.org>
# Date 2020-10-23 11:10:17
# Node ID 14ac6a74e7e749e5ca20f3ea8eb89460478ff9f6
# Parent  067707e026b406f68f95802f858de82d28976d70

ui: fix echo back of ui.prompt() to not concatenate None as bytes

Spotted while writing tests for the issue6425. The default value may be
None.

diff --git a/mercurial/ui.py b/mercurial/ui.py
--- a/mercurial/ui.py
+++ b/mercurial/ui.py
@@ -1659,7 +1659,9 @@ class ui(object):
             if not r:
                 r = default
             if self.configbool(b'ui', b'promptecho'):
-                self._writemsg(self._fmsgout, r, b"\n", type=b'promptecho')
+                self._writemsg(
+                    self._fmsgout, r or b'', b"\n", type=b'promptecho'
+                )
             return r
         except EOFError:
             raise error.ResponseExpected()