Following-up improvments for various PRs (#25620)

For:

* #22743
* #25408
* #25412
* #25588

models/git/branch.go

@@ -101,9 +101,9 @@ func (err ErrBranchesEqual) Unwrap() error {
 type Branch struct {
 	ID            int64
 	RepoID        int64  `xorm:"UNIQUE(s)"`
-	Name          string `xorm:"UNIQUE(s) NOT NULL"`
+	Name          string `xorm:"UNIQUE(s) NOT NULL"` // git's ref-name is case-sensitive internally, however, in some databases (mssql, mysql, by default), it's case-insensitive at the moment
 	CommitID      string
-	CommitMessage string `xorm:"TEXT"`
+	CommitMessage string `xorm:"TEXT"` // it only stores the message summary (the first line)
 	PusherID      int64
 	Pusher        *user_model.User `xorm:"-"`
 	IsDeleted     bool             `xorm:"index"`