git/Documentation/config/mailmap.txt

mailmap.file::
	The location of an augmenting mailmap file. The default
	mailmap, located in the root of the repository, is loaded
	first, then the mailmap file pointed to by this variable.
	The location of the mailmap file may be in a repository
	subdirectory, or somewhere outside of the repository itself.
	See linkgit:git-shortlog[1] and linkgit:git-blame[1].

mailmap.blob::
	Like `mailmap.file`, but consider the value as a reference to a
	blob in the repository. If both `mailmap.file` and
	`mailmap.blob` are given, both are parsed, with entries from
	`mailmap.file` taking precedence. In a bare repository, this
	defaults to `HEAD:.mailmap`. In a non-bare repository, it
	defaults to empty.