Try a forge clone again when its name lookup fails (issue 1773)

A build or check failed now and then on 'Could not resolve host:
novox.internal' between clones that resolved the same name, and its
whole delivery failed with it. A clone whose lookup failed reached
nothing, so it is cloned again with a growing pause for up to 60 s,
each retry said in the build's log as the resolver not answering;
past the bound it fails saying so. Any other git failure fails at
once, as before. Covers a module's own clone, an artifact's context
and a check's repositories.

internal/builder/builder.go

@@ -241,7 +241,8 @@ func build(ctx context.Context, run Runner, publish Publisher,
 	// A fresh clone every time rather than a fetch into a tree that is already there. A build
 	// that reuses a working tree can succeed because of something a previous build left behind,
 	// and that is a build nobody can reproduce.
-	if _, err := run(ctx, workspace, "git", cloneWith(credentials, "clone", "--quiet", repository, tree)...); err != nil {
+	if err := cloneFromForge(ctx, run, workspace, repository, tree,
+		cloneWith(credentials, "clone", "--quiet", repository, tree), say); err != nil {
 		say("clone", "FAILED: %v", err)
 		return Result{}, fmt.Errorf("cannot clone %s: %w", repository, err)
 	}
@@ -793,7 +794,7 @@ func contextFrom(ctx context.Context, run Runner, workspace, artifact, credentia
 			os.RemoveAll(dir)
 		}
 	}()
-	if _, err := run(ctx, workspace, "git", cloneWith(credentials, "clone", "--quiet", url, dir)...); err != nil {
+	if err := cloneFromForge(ctx, run, workspace, url, dir, cloneWith(credentials, "clone", "--quiet", url, dir), say); err != nil {
 		return "", fmt.Errorf("cannot clone %s: %w", url, err)
 	}
 	if err := recordedWithoutUserinfo(ctx, run, dir, url); err != nil {