Merge branch 'da/user-useconfigonly'

The "user.useConfigOnly" configuration variable can be used to
force the user to always set user.email & user.name configuration
variables, serving as a reminder for those who work on multiple
projects and do not want to put these in their $HOME/.gitconfig.

* da/user-useconfigonly:
  ident: add user.useConfigOnly boolean for when ident shouldn't be guessed
  fmt_ident: refactor strictness checks

Documentation/config.txt

@@ -2830,6 +2830,16 @@ user.name::
 	Can be overridden by the 'GIT_AUTHOR_NAME' and 'GIT_COMMITTER_NAME'
 	environment variables.  See linkgit:git-commit-tree[1].
 
+user.useConfigOnly::
+	Instruct Git to avoid trying to guess defaults for 'user.email'
+	and 'user.name', and instead retrieve the values only from the
+	configuration. For example, if you have multiple email addresses
+	and would like to use a different one for each repository, then
+	with this configuration option set to `true` in the global config
+	along with a name, Git will prompt you to set up an email before
+	making new commits in a newly cloned repository.
+	Defaults to `false`.
+
 user.signingKey::
 	If linkgit:git-tag[1] or linkgit:git-commit[1] is not selecting the
 	key you want it to automatically when creating a signed tag or