Use git log name-status in get last commit (#16059)

* Improve get last commit using git log --name-status

git log --name-status -c provides information about the diff between a
commit and its parents. Using this and adjusting the algorithm to use
the first change to a path allows for a much faster generation of commit
info.

There is a subtle change in the results generated but this will cause
the results to more closely match those from elsewhere.

Signed-off-by: Andrew Thornton <art27@cantab.net>

Co-authored-by: 6543 <6543@obermui.de>
Co-authored-by: techknowlogick <techknowlogick@gitea.io>
Co-authored-by: Lauris BH <lauris@nix.lv>

vendor/github.com/djherbis/buffer/partition.go

@@ -0,0 +1,101 @@
+package buffer
+
+import (
+	"encoding/gob"
+	"io"
+	"math"
+)
+
+type partition struct {
+	List
+	Pool
+}
+
+// NewPartition returns a Buffer which uses a Pool to extend or shrink its size as needed.
+// It automatically allocates new buffers with pool.Get() to extend is length, and
+// pool.Put() to release unused buffers as it shrinks.
+func NewPartition(pool Pool, buffers ...Buffer) Buffer {
+	return &partition{
+		Pool: pool,
+		List: buffers,
+	}
+}
+
+func (buf *partition) Cap() int64 {
+	return math.MaxInt64
+}
+
+func (buf *partition) Read(p []byte) (n int, err error) {
+	for len(p) > 0 {
+
+		if len(buf.List) == 0 {
+			return n, io.EOF
+		}
+
+		buffer := buf.List[0]
+
+		if Empty(buffer) {
+			buf.Pool.Put(buf.Pop())
+			continue
+		}
+
+		m, er := buffer.Read(p)
+		n += m
+		p = p[m:]
+
+		if er != nil && er != io.EOF {
+			return n, er
+		}
+
+	}
+	return n, nil
+}
+
+func (buf *partition) grow() error {
+	next, err := buf.Pool.Get()
+	if err != nil {
+		return err
+	}
+	buf.Push(next)
+	return nil
+}
+
+func (buf *partition) Write(p []byte) (n int, err error) {
+	for len(p) > 0 {
+
+		if len(buf.List) == 0 {
+			if err := buf.grow(); err != nil {
+				return n, err
+			}
+		}
+
+		buffer := buf.List[len(buf.List)-1]
+
+		if Full(buffer) {
+			if err := buf.grow(); err != nil {
+				return n, err
+			}
+			continue
+		}
+
+		m, er := buffer.Write(p)
+		n += m
+		p = p[m:]
+
+		if er != nil && er != io.ErrShortWrite {
+			return n, er
+		}
+
+	}
+	return n, nil
+}
+
+func (buf *partition) Reset() {
+	for len(buf.List) > 0 {
+		buf.Pool.Put(buf.Pop())
+	}
+}
+
+func init() {
+	gob.Register(&partition{})
+}