[PATCH] commit: document the ui.allowemptycommit option

[Jordi Gutiérrez Hermoso]

# HG changeset patch
# User Jordi Gutiérrez Hermoso <jordigh at octave.org>
# Date 1451506458 18000
#      Wed Dec 30 15:14:18 2015 -0500
# Node ID 36b8f8e0a55be1e6ad3356d4b0177712ba62617b
# Parent  23541bdd1610c08af247f9c8719045cf247ce541
commit: document the ui.allowemptycommit option

It may be nice to document the situations in which other commands
create empty commits, but I did not think it was necessary to go into
that much detail.

diff --git a/mercurial/commands.py b/mercurial/commands.py
--- a/mercurial/commands.py
+++ b/mercurial/commands.py
@@ -1581,6 +1581,10 @@ def commit(ui, repo, *pats, **opts):
     commit fails, you will find a backup of your message in
     ``.hg/last-message.txt``.
 
+    Empty commits by default are not allowed. You may enable the
+    creation of empty commits via the ``ui.allowemptycommit``
+    configuration option (see :hg:`help config`).
+
     The --close-branch flag can be used to mark the current branch
     head closed. When all heads of a branch are closed, the branch
     will be considered closed and no longer listed.
diff --git a/mercurial/help/config.txt b/mercurial/help/config.txt
--- a/mercurial/help/config.txt
+++ b/mercurial/help/config.txt
@@ -1441,6 +1441,13 @@ user or service running Mercurial.
 
 User interface controls.
 
+``allowemptycommit``
+    Whether to allow creation of empty commits by the ordinary ``hg
+    commit`` command. An empty commit is a commit that does not modify
+    any files and is not a merge commit. Note that some other commands
+    may still produce empty commits regardless of this setting.
+    (default: False)
+
 ``archivemeta``
     Whether to include the .hg_archival.txt file containing meta data
     (hashes for the repository base and for tip) in archives created