Regresion test case: Empty lines in patch descriptions were
accidentally removed.

	$ mkdir d
	$ cd d
	$ mkdir patches
	$ echo one > f
	$ cat > patches/test.diff
	< C1
	<
	< C3
	<
	< Index: f
	< ===================================================================
	< --- f.orig	foo
	< +++ f	bar
	< @@ -1 +1 @@
	< -one
	< +two

	$ cat > patches/series
	< test.diff -p0 # What a wonderful patch

	$ quilt push
	> Applying patch %{P}test.diff
	> patching file f
	>
	> Now at patch %{P}test.diff

	$ quilt refresh
	> Refreshed patch %{P}test.diff
	$ cat patches/test.diff
	> C1
	>
	> C3
	>
	> Index: f
	> ===================================================================
	> --- f.orig
	> +++ f
	> @@ -1 +1 @@
	> -one
	> +two

	$ quilt refresh -c
	> Refreshed patch %{P}test.diff

	$ cat patches/test.diff
	> C1
	>
	> C3
	>
	> Index: f
	> ===================================================================
	> *** f.orig
	> --- f
	> ***************
	> *** 1 ****
	> ! one
	> --- 1 ----
	> ! two
	
	$ quilt refresh
	> Refreshed patch %{P}test.diff
	
	$ cat patches/test.diff
	> C1
	>
	> C3
	>
	> Index: f
	> ===================================================================
	> --- f.orig
	> +++ f
	> @@ -1 +1 @@
	> -one
	> +two
	$ cd ..
	$ rm -rf d