ui: ensure `getpass()` returns bytes

Previously, this could return either bytes or str.  I'm not sure which direction
we should go in, but since the input is bytes, I guess bytes makes sense as
output.  `debuguigetpass` crashed because it assumed bytes would be returned,
`sslcontext.load_cert_chain()` is happy with bytes or str if the type info in
PyCharm is correct, and `smtplib.SMTP.login()` wants str.

I couldn't figure out how to test this, because the test stalls for input with
`echo test | hg debuguigetpass --config ui.interactive=1`, likely because it
drains stdin before prompting.  The custom input reading with `ui.nontty=1` does
not.

I'm also a bit concerned with all of this encoding/decoding.  The existing code
in the mail module uses `encoding.strfromlocal()`, but the username and password
are ascii encoded/decoded in `mercurial.url.passwordmgr.find_user_password()`
with `pycompat.{str,bytes}url()`.  I'm not sure if this inconsistency could
cause subtle compatability issues.

Differential Revision: https://phab.mercurial-scm.org/D9375

mercurial/debugcommands.py

@@ -3787,6 +3787,10 b' def debugtemplate(ui, repo, tmpl, **opts'
 def debuguigetpass(ui, prompt=b''):
     """show prompt to type password"""
     r = ui.getpass(prompt)
+    if r is not None:
+        r = encoding.strtolocal(r)
+    else:
+        r = b"<default response>"
     ui.writenoi18n(b'response: %s\n' % r)
 
 

mercurial/mail.py

@@ -157,6 +157,8 b' def _smtp(ui):'
             password = encoding.strfromlocal(password)
         else:
             password = ui.getpass()
+            if password is not None:
+                password = encoding.strfromlocal(password)
     if username and password:
         ui.note(_(b'(authenticating to mail server as %s)\n') % username)
         username = encoding.strfromlocal(username)

mercurial/ui.py

@@ -1735,7 +1735,7 b' class ui(object):'
                         raise EOFError
                     return l.rstrip(b'\n')
                 else:
-                    return getpass.getpass('')
+                    return encoding.strtolocal(getpass.getpass(''))
         except EOFError:
             raise error.ResponseExpected()