Fix parse error against diffstat in git format-patch

The parser was not accepting diffstat from git format-patch files.
This patch fixes this issue and rewrites the git.diff file to contain
the full output of a git format-patch command to exercise the parser
(minus the git version, as this would trigger an assert error because of
remaining content).

Fixes uniphil#27

Author: gagath

src/parser.rs

@@ -116,7 +116,7 @@ fn patch(input: Input<'_>) -> IResult<Input<'_>, Patch> {
 // Header lines
 fn headers(input: Input<'_>) -> IResult<Input<'_>, (File, File)> {
     // Ignore any preamble lines in produced diffs
-    let (input, _) = take_until("---")(input)?;
+    let (input, _) = take_until("--- ")(input)?;
     let (input, _) = tag("--- ")(input)?;
     let (input, oldfile) = header_line_content(input)?;
     let (input, _) = line_ending(input)?;

tests/samples/git.diff

@@ -1,16 +1,18 @@
-diff --git a/added_file b/added_file
-new file mode 100644
-index 0000000..9b710f3
---- /dev/null
-+++ b/added_file
-@@ -0,0 +1,4 @@
-+This was missing!
-+Adding it now.
-+
-+Only for testing purposes.
-\ No newline at end of file
+From c285d896b6ef509291860351d246e82a83e9d96a Mon Sep 17 00:00:00 2001
+From: Foo Bar <[email protected]>
+Date: Mon, 9 Sep 2024 21:14:30 +0200
+Subject: [PATCH] Test commit
+
+---
+ modified_file | 4 +++-
+ new_file      | 4 ++++
+ removed_file  | 3 ---
+ 3 files changed, 7 insertions(+), 4 deletions(-)
+ create mode 100644 new_file
+ delete mode 100644 removed_file
+
 diff --git a/modified_file b/modified_file
-index c7921f5..8946660 100644
+index c368d8f..922fd19 100644
 --- a/modified_file
 +++ b/modified_file
 @@ -1,5 +1,7 @@
@@ -22,15 +24,23 @@ index c7921f5..8946660 100644
 +This is a new line.
 
  This will stay.
-\ No newline at end of file
+diff --git a/new_file b/new_file
+new file mode 100644
+index 0000000..7056bca
+--- /dev/null
++++ b/new_file
+@@ -0,0 +1,4 @@
++This was missing!
++Adding it now.
++
++Only for testing purposes.
 diff --git a/removed_file b/removed_file
 deleted file mode 100644
-index 1f38447..0000000
+index 9b89750..0000000
 --- a/removed_file
 +++ /dev/null
 @@ -1,3 +0,0 @@
 -This content shouldn't be here.
 -
 -This file will be removed.
-\ No newline at end of file