Merge branch 'jk/pretty-lazy-load-commit'

Some pretty-format specifiers do not need the data in commit object
(e.g. "%H"), but we were over-eager to load and parse it, which has
been made even lazier.

* jk/pretty-lazy-load-commit:
  pretty: lazy-load commit data when expanding user-format

t/perf/p4205-log-pretty-formats.sh

@@ -6,7 +6,7 @@ test_description='Tests the performance of various pretty format placeholders'
 
 test_perf_default_repo
 
-for format in %H %h %T %t %P %p %h-%h-%h
+for format in %H %h %T %t %P %p %h-%h-%h %an-%ae-%s
 do
 	test_perf "log with $format" "
 		git log --format=\"$format\" >/dev/null