Merge branch 'jc/show-branch-g-current' into maint

The "--current" option of "git show-branch" should have been made
incompatible with the "--reflog" mode, but this was not enforced,
which has been corrected.
source: <xmqqh76mf7s4.fsf_-_@gitster.g>

* jc/show-branch-g-current:
  show-branch: -g and --current are incompatible

builtin/show-branch.c

@@ -712,6 +712,10 @@ int cmd_show_branch(int ac, const char **av, const char *prefix)
 				"--all/--remotes/--independent/--merge-base");
 	}
 
+	if (with_current_branch && reflog)
+		die(_("options '%s' and '%s' cannot be used together"),
+		    "--reflog", "--current");
+
 	/* If nothing is specified, show all branches by default */
 	if (ac <= topics && all_heads + all_remotes == 0)
 		all_heads = 1;

t/t3202-show-branch.sh

@@ -161,4 +161,18 @@ test_expect_success 'show branch --reflog=2' '
 	test_cmp actual expect
 '
 
+# incompatible options
+while read combo
+do
+	test_expect_success "show-branch $combo (should fail)" '
+		test_must_fail git show-branch $combo 2>error &&
+		grep -e "cannot be used together" -e "usage:" error
+	'
+done <<\EOF
+--all --reflog
+--merge-base --reflog
+--list --merge-base
+--reflog --current
+EOF
+
 test_done