build zsh without wrapper scripts

Using a wrapper makes zsh login shells incorrectly detect that they are not a
login shell, which in turn breaks debugging with gdb (behaving as if “stty
tostop” was enabled).

internal/build/build.go

@@ -1372,10 +1372,15 @@ func (b *Ctx) Build(ctx context.Context, buildLog io.Writer) (*pb.Meta, error) {
 			} else {
 				oldname := filepath.Join(dir, fi.Name())
 
-				if b.Pkg == "bash" && (fi.Name() == "sh" || fi.Name() == "bash") {
+				if b.Pkg == "bash" && (fi.Name() == "sh" || fi.Name() == "bash") ||
+					b.Pkg == "zsh" && (fi.Name() == "zsh" || strings.HasPrefix(fi.Name(), "zsh-")) {
 					// prevent creation of a wrapper script for /bin/sh
 					// (wrappers execute /bin/sh) and /bin/bash (dracut uses
-					// /bin/bash) by using a symlink instead:
+					// /bin/bash) by using a symlink instead.
+					//
+					// zsh must not be wrapped, otherwise setting /bin/zsh as
+					// login shell results in shell instances which do not
+					// consider themselves to be a login shell.
 					oldname, err = filepath.Rel(filepath.Join(b.DestDir, b.Prefix, "bin"), oldname)
 					if err != nil {
 						return nil, err

pkgs/base-cloud/build.textproto

@@ -1,5 +1,5 @@
 source: "empty://"
-version: "1-14"
+version: "1-15"
 
 # This is the shortest and fastest way to build an empty package:
 dep: "bash"

pkgs/base-full/build.textproto

@@ -1,5 +1,5 @@
 source: "empty://"
-version: "3-19"
+version: "3-20"
 
 # This is the shortest and fastest way to build an empty package:
 dep: "bash"

pkgs/base-x11/build.textproto

@@ -1,5 +1,5 @@
 source: "empty://"
-version: "2-22"
+version: "2-23"
 
 # This is the shortest and fastest way to build an empty package:
 dep: "bash"

pkgs/zsh/build.textproto

@@ -1,6 +1,6 @@
 source: "https://repo.distr1.org/distri/jackherer/orig/zsh/zsh-5.6.2.tar.xz"
 hash: "a50bd66c0557e8eca3b8fa24e85d0de533e775d7a22df042da90488623752e9e"
-version: "5.6.2-7"
+version: "5.6.2-8"
 
 cbuilder: {
   copy_to_builddir: true  # TODO: patch Doc/Makefile.in to use $(sdir)/help.txt