Merge branch 'jn/ident-from-etc-mailname'

* jn/ident-from-etc-mailname:
ident: do not retrieve default ident when unnecessary
ident: check /etc/mailname if email is unknown

diff --combined Documentation/git-commit-tree.txt
index 0fdb82ee8697a53beab6defd4db9eca8840b1dd0,9ac30a3274a21461589da65ee3e130c3f0b73950..02133d5fc9a14df7f4fe24d97bdf9980e77f807a
--- 1/Documentation/git-commit-tree.txt
--- 2/Documentation/git-commit-tree.txt
+++ b/Documentation/git-commit-tree.txt
@@@ -8,7 -8,6 +8,7 @@@ git-commit-tree - Create a new commit o
  
  SYNOPSIS
  --------
 +[verse]
  'git commit-tree' <tree> [(-p <parent commit>)...] < changelog
  
  DESCRIPTION
@@@ -68,7 -67,9 +68,9 @@@ if set
  
  In case (some of) these environment variables are not set, the information
  is taken from the configuration items user.name and user.email, or, if not
- present, system user name and fully qualified hostname.
+ present, system user name and the hostname used for outgoing mail (taken
+ from `/etc/mailname` and falling back to the fully qualified hostname when
+ that file does not exist).
  
  A commit comment is read from stdin. If a changelog
  entry is not provided via "<" redirection, 'git commit-tree' will just wait
@@@ -90,6 -91,10 +92,10 @@@ Discussio
  
  include::i18n.txt[]
  
+ FILES
+ -----
+ /etc/mailname
+ 
  SEE ALSO
  --------
  linkgit:git-write-tree[1]