Add --oneline that is a synonym to "--pretty=oneline --abbrev-commit"

These two are often used together but are too long to type.

Signed-off-by: Nanako Shiraishi <nanako3@lavabit.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/pretty-options.txt

@@ -18,6 +18,10 @@ configuration (see linkgit:git-config[1]).
 This should make "--pretty=oneline" a whole lot more readable for
 people using 80-column terminals.
 
+--oneline::
+	This is a shorthand for "--pretty=oneline --abbrev-commit"
+	used together.
+
 --encoding[=<encoding>]::
 	The commit objects record the encoding used for the log message
 	in their encoding header; this option can be used to tell the

revision.c

@@ -1147,6 +1147,10 @@ static int handle_revision_opt(struct rev_info *revs, int argc, const char **arg
 	} else if (!prefixcmp(arg, "--pretty=") || !prefixcmp(arg, "--format=")) {
 		revs->verbose_header = 1;
 		get_commit_format(arg+9, revs);
+	} else if (!strcmp(arg, "--oneline")) {
+		revs->verbose_header = 1;
+		get_commit_format("oneline", revs);
+		revs->abbrev_commit = 1;
 	} else if (!strcmp(arg, "--graph")) {
 		revs->topo_order = 1;
 		revs->rewrite_parents = 1;