Merge branch 'jn/mergetool-hideresolved-is-optional'

Disable the recent mergetool's hideresolved feature by default for
backward compatibility and safety.

* jn/mergetool-hideresolved-is-optional:
  doc: describe mergetool configuration in git-mergetool(1)
  mergetool: do not enable hideResolved by default

Documentation/config/mergetool.txt

@@ -53,7 +53,7 @@ mergetool.hideResolved::
 	resolution. This flag causes 'LOCAL' and 'REMOTE' to be overwriten so
 	that only the unresolved conflicts are presented to the merge tool. Can
 	be configured per-tool via the `mergetool.<tool>.hideResolved`
-	configuration variable. Defaults to `true`.
+	configuration variable. Defaults to `false`.
 
 mergetool.keepBackup::
 	After performing a merge, the original file with conflict markers

Documentation/git-mergetool.txt

@@ -99,6 +99,10 @@ success of the resolution after the custom tool has exited.
 	(see linkgit:git-config[1]).  To cancel `diff.orderFile`,
 	use `-O/dev/null`.
 
+CONFIGURATION
+-------------
+include::config/mergetool.txt[]
+
 TEMPORARY FILES
 ---------------
 `git mergetool` creates `*.orig` backup files while resolving merges.

git-mergetool.sh

@@ -358,13 +358,8 @@ merge_file () {
 		    enabled=false
 		fi
 	else
-		# The user does not have a preference. Ask the tool.
-		if hide_resolved_enabled
-		then
-		    enabled=true
-		else
-		    enabled=false
-		fi
+		# The user does not have a preference. Default to disabled.
+		enabled=false
 	fi
 
 	if test "$enabled" = true