diff --git a/src/Pure/General/sha1.scala b/src/Pure/General/sha1.scala
--- a/src/Pure/General/sha1.scala
+++ b/src/Pure/General/sha1.scala
@@ -1,87 +1,89 @@
 /*  Title:      Pure/General/sha1.scala
     Author:     Makarius
 
 SHA-1 message digest according to RFC 3174.
 */
 
 package isabelle
 
 
 import java.io.{File => JFile, FileInputStream}
 import java.security.MessageDigest
 
 import isabelle.setup.{Build => Setup_Build}
 
 
 object SHA1 {
   /* digest */
 
   final class Digest private[SHA1](rep: String) {
     override def toString: String = rep
     override def hashCode: Int = rep.hashCode
     override def equals(that: Any): Boolean =
       that match {
         case other: Digest => rep == other.toString
         case _ => false
       }
   }
 
   def fake_digest(rep: String): Digest = new Digest(rep)
 
   def make_digest(body: MessageDigest => Unit): Digest = {
     val digest_body = new Setup_Build.Digest_Body { def apply(sha: MessageDigest): Unit = body(sha)}
     new Digest(Setup_Build.make_digest(digest_body))
   }
 
   def digest(file: JFile): Digest =
     make_digest(sha => using(new FileInputStream(file)) { stream =>
       val buf = new Array[Byte](65536)
       var m = 0
       while ({
         m = stream.read(buf, 0, buf.length)
         if (m != -1) sha.update(buf, 0, m)
         m != -1
       }) ()
     })
 
   def digest(path: Path): Digest = digest(path.file)
   def digest(bytes: Array[Byte]): Digest = make_digest(_.update(bytes))
   def digest(bytes: Bytes): Digest = bytes.sha1_digest
   def digest(string: String): Digest = digest(Bytes(string))
   def digest_set(digests: List[Digest]): Digest =
     digest(cat_lines(digests.map(_.toString).sorted))
 
   val digest_length: Int = digest("").toString.length
 
 
   /* shasum */
 
   final class Shasum private[SHA1](private[SHA1] val rep: List[String]) {
     override def equals(other: Any): Boolean =
       other match {
         case that: Shasum => rep.equals(that.rep)
         case _ => false
       }
     override def hashCode: Int = rep.hashCode
     override def toString: String = Library.terminate_lines(rep)
 
     def is_empty: Boolean = rep.isEmpty
 
     def digest: Digest = {
       rep match {
         case List(s)
         if s.length == digest_length && s.forall(Symbol.is_ascii_hex) => fake_digest(s)
         case _ => SHA1.digest(toString)
       }
     }
   }
 
   val no_shasum: Shasum = new Shasum(Nil)
   def flat_shasum(list: List[Shasum]): Shasum = new Shasum(list.flatMap(_.rep))
   def fake_shasum(text: String): Shasum = new Shasum(Library.trim_split_lines(text))
 
-  def shasum(digest: Digest, name: String): Shasum = new Shasum(List(digest.toString + " " + name))
-  def shasum_meta_info(digest: Digest): Shasum = shasum(digest, isabelle.setup.Build.META_INFO)
+  def shasum(digest: Digest, name: String): Shasum =
+    new Shasum(List(digest.toString + " " + name))
+  def shasum_meta_info(digest: Digest): Shasum =
+    shasum(digest, isabelle.setup.Build.META_INFO)
   def shasum_sorted(args: List[(Digest, String)]): Shasum =
     flat_shasum(args.sortBy(_._2).map(shasum))
 }