plain: ignore [commands] config

We only have commands.{update,rebase}.requiredest so far. We should
clearly ignore those two if HGPLAIN is in effect, and it seems like we
should ignore any future config that will be added in [commands] since
that is about changing the behavior of commands.

Thanks to Yuya for suggesting to centralize the code in ui.py.

While at it, remove the unnecessary False values passed to
ui.configbool() for the aforementioned config options.

hgext/rebase.py

@@ -686,7 +686,7 b' def rebase(ui, repo, **opts):'
         # Validate input and define rebasing points
         destf = opts.get('dest', None)
 
-        if ui.config('commands', 'rebase.requiredest', False):
+        if ui.config('commands', 'rebase.requiredest'):
             if not destf:
                 raise error.Abort(_('you must specify a destination'),
                                   hint=_('use: hg rebase -d REV'))

mercurial/commands.py

@@ -5349,7 +5349,7 b' def update(ui, repo, node=None, rev=None'
     if rev and node:
         raise error.Abort(_("please specify just one revision"))
 
-    if ui.configbool('commands', 'update.requiredest', False):
+    if ui.configbool('commands', 'update.requiredest'):
         if not node and not rev and not date:
             raise error.Abort(_('you must specify a destination'),
                               hint=_('for example: hg update ".::"'))

mercurial/ui.py

@@ -284,6 +284,8 b' class ui(object):'
                     del cfg['ui'][k]
             for k, v in cfg.items('defaults'):
                 del cfg['defaults'][k]
+            for k, v in cfg.items('commands'):
+                del cfg['commands'][k]
         # Don't remove aliases from the configuration if in the exceptionlist
         if self.plain('alias'):
             for k, v in cfg.items('alias'):

tests/test-rebase-base.t

@@ -413,3 +413,7 b' Require a destination'
   $ hg rebase -d 1
   rebasing 2:5db65b93a12b "cc" (tip)
   saved backup bundle to $TESTTMP/repo/.hg/strip-backup/5db65b93a12b-4fb789ec-backup.hg (glob)
+  $ hg rebase -d 0 -r . -q
+  $ HGPLAIN=1 hg rebase
+  rebasing 2:889b0bc6a730 "cc" (tip)
+  saved backup bundle to $TESTTMP/repo/.hg/strip-backup/889b0bc6a730-41ec4f81-backup.hg (glob)

tests/test-update-names.t

@@ -104,3 +104,5 b' Test that warning is printed if cwd is d'
   [255]
   $ hg up .
   0 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  $ HGPLAIN=1 hg up
+  0 files updated, 0 files merged, 0 files removed, 0 files unresolved