Sync with 2.4.2

diff --combined Documentation/git.txt
index 38cc004065a6f8a00dc5014de5b732dc57e8d114,f582742bc81a761218f30cead342491cf5580a5d..ccc12b280652609bfd5eb089e194a9219b7fc9f2
--- 1/Documentation/git.txt
--- 2/Documentation/git.txt
+++ b/Documentation/git.txt
@@@ -43,9 -43,10 +43,10 @@@ unreleased) version of Git, that is ava
  branch of the `git.git` repository.
  Documentation for older releases are available here:
  
- * link:v2.4.1/git.html[documentation for release 2.4.1]
+ * link:v2.4.2/git.html[documentation for release 2.4.2]
  
  * release notes for
+   link:RelNotes/2.4.2.txt[2.4.2],
    link:RelNotes/2.4.1.txt[2.4.1],
    link:RelNotes/2.4.0.txt[2.4].
  
@@@ -835,15 -836,6 +836,15 @@@ Git so take care if using Cogito etc
        an explicit repository directory set via 'GIT_DIR' or on the
        command line.
  
 +'GIT_COMMON_DIR'::
 +      If this variable is set to a path, non-worktree files that are
 +      normally in $GIT_DIR will be taken from this path
 +      instead. Worktree-specific files such as HEAD or index are
 +      taken from $GIT_DIR. See linkgit:gitrepository-layout[5] and
 +      the section 'MULTIPLE CHECKOUT MODE' in linkgit:checkout[1]
 +      details. This variable has lower precedence than other path
 +      variables such as GIT_INDEX_FILE, GIT_OBJECT_DIRECTORY...
 +
  Git Commits
  ~~~~~~~~~~~
  'GIT_AUTHOR_NAME'::