Make the deprecated forget an alias of debugforget.

This way it doesn't show up in the non-debug help.

mercurial/commands.py

@@ -2978,7 +2978,7 b' table = {'
           ('a', 'text', None, _('treat all files as text')),
           ('', 'switch-parent', None, _('diff against the second parent'))],
          _('hg export [-a] [-o OUTFILESPEC] REV...')),
-    "forget":
+    "debugforget|forget":
         (forget,
          [('I', 'include', [], _('include names matching the given patterns')),
           ('X', 'exclude', [], _('exclude names matching the given patterns'))],

tests/test-help.out

@@ -49,7 +49,6 b' list of commands (use "hg help -v" to sh'
  copy        mark files as copied for the next commit
  diff        diff repository (or selected files)
  export      dump the header and diffs for one or more changesets
- forget      don't add the specified files on the next commit (DEPRECATED)
  grep        search for a pattern in specified files and revisions
  heads       show current repository heads
  help        show help for a given command or all commands
@@ -92,7 +91,6 b' list of commands (use "hg help -v" to sh'
  copy        mark files as copied for the next commit
  diff        diff repository (or selected files)
  export      dump the header and diffs for one or more changesets
- forget      don't add the specified files on the next commit (DEPRECATED)
  grep        search for a pattern in specified files and revisions
  heads       show current repository heads
  help        show help for a given command or all commands