Merge branch 'jk/filter-branch-use-of-sed-on-incomplete-line' into maint

A recent "filter-branch --msg-filter" broke skipping of the commit
object header, which is fixed.

* jk/filter-branch-use-of-sed-on-incomplete-line:
  filter-branch: remove multi-line headers in msg filter

git-filter-branch.sh

@@ -347,7 +347,7 @@ while read commit parents; do
 	fi
 
 	{
-		while read -r header_line && test -n "$header_line"
+		while IFS='' read -r header_line && test -n "$header_line"
 		do
 			# skip header lines...
 			:;

t/t7003-filter-branch.sh

@@ -2,6 +2,7 @@
 
 test_description='git filter-branch'
 . ./test-lib.sh
+. "$TEST_DIRECTORY/lib-gpg.sh"
 
 test_expect_success 'setup' '
 	test_commit A &&
@@ -292,6 +293,19 @@ test_expect_success 'Tag name filtering strips gpg signature' '
 	test_cmp expect actual
 '
 
+test_expect_success GPG 'Filtering retains message of gpg signed commit' '
+	mkdir gpg &&
+	touch gpg/foo &&
+	git add gpg &&
+	test_tick &&
+	git commit -S -m "Adding gpg" &&
+
+	git log -1 --format="%s" > expect &&
+	git filter-branch -f --msg-filter "cat" &&
+	git log -1 --format="%s" > actual &&
+	test_cmp expect actual
+'
+
 test_expect_success 'Tag name filtering allows slashes in tag names' '
 	git tag -m tag-with-slash X/1 &&
 	git cat-file tag X/1 | sed -e s,X/1,X/2, > expect &&