chistedit: improve proper username in histedit curses interface

in changeset section (issue6072)

Differential Revision: https://phab.mercurial-scm.org/D5967

hgext/histedit.py

@@ -1260,7 +1260,7 b' def _chisteditmain(repo, rules, stdscr):'
         line = "changeset: {0}:{1:<12}".format(ctx.rev(), ctx)
         win.addstr(1, 1, line[:length])
 
-        line = "user:      {0}".format(stringutil.shortuser(ctx.user()))
+        line = "user:      {0}".format(ctx.user())
         win.addstr(2, 1, line[:length])
 
         bms = repo.nodebookmarks(ctx.node())