fix: Proper paring of date for git commits

- Properly parse the date of the git commit and pass that around.

modules/gitgraph/graph.go

@@ -16,7 +16,7 @@ import (
 
 // GetCommitGraph return a list of commit (GraphItems) from all branches
 func GetCommitGraph(r *git.Repository, page, maxAllowedColors int, hidePRRefs bool, branches, files []string) (*Graph, error) {
-	format := "DATA:%D|%H|%ad|%h|%s"
+	format := "DATA:%D|%H|%aD|%h|%s"
 
 	if page == 0 {
 		page = 1

modules/gitgraph/graph_models.go

@@ -8,6 +8,7 @@ import (
 	"context"
 	"fmt"
 	"strings"
+	"time"
 
 	asymkey_model "code.gitea.io/gitea/models/asymkey"
 	"code.gitea.io/gitea/models/db"
@@ -198,6 +199,11 @@ func NewCommit(row, column int, line []byte) (*Commit, error) {
 	if len(data) < 5 {
 		return nil, fmt.Errorf("malformed data section on line %d with commit: %s", row, string(line))
 	}
+	// Format is a slight modifcation from RFC1123Z
+	t, err := time.Parse("Mon, _2 Jan 2006 15:04:05 -0700", string(data[2]))
+	if err != nil {
+		return nil, fmt.Errorf("could not parse date of commit: %w", err)
+	}
 	return &Commit{
 		Row:    row,
 		Column: column,
@@ -205,8 +211,8 @@ func NewCommit(row, column int, line []byte) (*Commit, error) {
 		Refs: newRefsFromRefNames(data[0]),
 		// 1 matches git log --pretty=format:%H => commit hash
 		Rev: string(data[1]),
-		// 2 matches git log --pretty=format:%ad => author date (format respects --date= option)
-		Date: string(data[2]),
+		// 2 matches git log --pretty=format:%aD => author date, RFC2822 style
+		Date: t,
 		// 3 matches git log --pretty=format:%h => abbreviated commit hash
 		ShortRev: string(data[3]),
 		// 4 matches git log --pretty=format:%s => subject
@@ -245,7 +251,7 @@ type Commit struct {
 	Column       int
 	Refs         []git.Reference
 	Rev          string
-	Date         string
+	Date         time.Time
 	ShortRev     string
 	Subject      string
 }

modules/gitgraph/graph_test.go

@@ -241,7 +241,7 @@ func TestParseGlyphs(t *testing.T) {
 }
 
 func TestCommitStringParsing(t *testing.T) {
-	dataFirstPart := "* DATA:|4e61bacab44e9b4730e44a6615d04098dd3a8eaf|2016-12-20 21:10:41 +0100|4e61bac|"
+	dataFirstPart := "* DATA:|4e61bacab44e9b4730e44a6615d04098dd3a8eaf|Tue, 20 Dec 2016 21:10:41 +0100|4e61bac|"
 	tests := []struct {
 		shouldPass    bool
 		testName      string