Merge branch 'jk/no-optional-locks'

Some commands (most notably "git status") makes an opportunistic
update when performing a read-only operation to help optimize later
operations in the same repository.  The new "--no-optional-locks"
option can be passed to Git to disable them.

* jk/no-optional-locks:
  git: add --no-optional-locks option

Documentation/git.txt

@@ -159,6 +159,10 @@ foo.bar= ...`) sets `foo.bar` to the empty string which ` git config
 	Add "icase" magic to all pathspec. This is equivalent to setting
 	the `GIT_ICASE_PATHSPECS` environment variable to `1`.
 
+--no-optional-locks::
+	Do not perform optional operations that require locks. This is
+	equivalent to setting the `GIT_OPTIONAL_LOCKS` to `0`.
+
 GIT COMMANDS
 ------------
 
@@ -697,6 +701,14 @@ of clones and fetches.
 	which feed potentially-untrusted URLS to git commands.  See
 	linkgit:git-config[1] for more details.
 
+`GIT_OPTIONAL_LOCKS`::
+	If set to `0`, Git will complete any requested operation without
+	performing any optional sub-operations that require taking a lock.
+	For example, this will prevent `git status` from refreshing the
+	index as a side effect. This is useful for processes running in
+	the background which do not want to cause lock contention with
+	other operations on the repository.  Defaults to `1`.
+
 Discussion[[Discussion]]
 ------------------------