t4205 (log-pretty-formats): don't hardcode SHA-1 in expected outputs

The expected SHA-1 digests are always available in variables. Use
them instead of hardcoding.

That was introduced in a742f2a (t4205 (log-pretty-formats): don't
hardcode SHA-1 in expected outputs, 2013-06-26) but unfortunately was
not followed in 5e1361c (log: properly handle decorations with chained
tags, 2013-12-17)

Signed-off-by: Alexey Shumkin <Alex.Crezoff@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t4205-log-pretty-formats.sh

@@ -296,6 +296,10 @@ EOF
 	test_cmp expected actual
 '
 
+# save HEAD's SHA-1 digest (with no abbreviations) to use it below
+# as far as the next test amends HEAD
+old_head1=$(git rev-parse --verify HEAD~0)
+
 test_expect_success 'left/right alignment formatting with stealing' '
 	git commit --amend -m short --author "long long long <long@me.com>" &&
 	git log --pretty="format:%<(10,trunc)%s%>>(10,ltrunc)% an" >actual &&
@@ -310,6 +314,10 @@ EOF
 	test_cmp expected actual
 '
 
+# get new digests (with no abbreviations)
+head1=$(git rev-parse --verify HEAD~0) &&
+head2=$(git rev-parse --verify HEAD~1) &&
+
 test_expect_success 'log decoration properly follows tag chain' '
 	git tag -a tag1 -m tag1 &&
 	git tag -a tag2 -m tag2 tag1 &&
@@ -317,9 +325,9 @@ test_expect_success 'log decoration properly follows tag chain' '
 	git commit --amend -m shorter &&
 	git log --no-walk --tags --pretty="%H %d" --decorate=full >actual &&
 	cat <<EOF >expected &&
-6a908c10688b2503073c39c9ba26322c73902bb5  (tag: refs/tags/tag2)
-9f716384d92283fb915a4eee5073f030638e05f9  (tag: refs/tags/message-one)
-b87e4cccdb77336ea79d89224737be7ea8e95367  (tag: refs/tags/message-two)
+$head1  (tag: refs/tags/tag2)
+$head2  (tag: refs/tags/message-one)
+$old_head1  (tag: refs/tags/message-two)
 EOF
 	sort actual >actual1 &&
 	test_cmp expected actual1