Stop copying qemu-$arch-static binary into the chroot

- since qemu-user binfmt has support for pre-opening the interpreter
   since stretch, there is no reason to copy it into the chroot anymore

mmdebstrap

@@ -2772,11 +2772,10 @@ sub run_prepare {
         error "unknown mode: $options->{mode}";
     }
 
-    # copy qemu-user-static binary into chroot
+    # foreign architecture setup for fakechroot mode
-    if (defined $options->{qemu}) {
+    if (defined $options->{qemu} && $options->{mode} eq 'fakechroot') {
-        if ($options->{mode} eq 'fakechroot') {
+        # Make sure that the fakeroot and fakechroot shared libraries exist for
-            # Make sure that the fakeroot and fakechroot shared
+        # the right architecture
-            # libraries exist for the right architecture
         open my $fh, '-|', 'dpkg-architecture', '-a',
           $options->{nativearch},
           '-qDEB_HOST_MULTIARCH' // error "failed to fork(): $!";
@@ -2799,64 +2798,24 @@ sub run_prepare {
               . " Install libfakeroot:$options->{nativearch}"
               . " outside the chroot";
         }
-            # The rest of this block sets environment variables, so we
+
-            # have to add the "no critic" statement to stop perlcritic
+        # The rest of this block sets environment variables, so we have to add
-            # from complaining about setting global variables
+        # the "no critic" statement to stop perlcritic from complaining about
+        # setting global variables
         ## no critic (Variables::RequireLocalizedPunctuationVars)
-            # fakechroot only fills LD_LIBRARY_PATH with the
+        # fakechroot only fills LD_LIBRARY_PATH with the directories of the
-            # directories of the host's architecture. We append the
+        # host's architecture. We append the directories of the chroot
-            # directories of the chroot architecture.
+        # architecture.
         $ENV{LD_LIBRARY_PATH}
           = "$ENV{LD_LIBRARY_PATH}:$fakechrootdir:$fakerootdir";
-            # The binfmt support on the outside is used, so qemu needs
+        # The binfmt support on the outside is used, so qemu needs to know
-            # to know where it has to look for shared libraries
+        # where it has to look for shared libraries
         if (defined $ENV{QEMU_LD_PREFIX}
             && $ENV{QEMU_LD_PREFIX} ne "") {
             $ENV{QEMU_LD_PREFIX} = "$ENV{QEMU_LD_PREFIX}:$options->{root}";
         } else {
             $ENV{QEMU_LD_PREFIX} = $options->{root};
         }
-        } elsif (any { $_ eq $options->{mode} } ('root', 'unshare')) {
-            my $require_qemu_static = 1;
-            # make $@ local, so we don't print an eventual error
-            # in other parts where we evaluate $@
-            local $@ = '';
-            eval {
-                # Check for the F flag which makes the kernel open the binfmt
-                # binary at configuration time instead of lazily at startup
-                # time. If the flag is set, then the qemu-static binary is not
-                # required inside the chroot.
-                if (-e "/proc/sys/fs/binfmt_misc/qemu-$options->{qemu}") {
-                    open my $fh, '<',
-                      "/proc/sys/fs/binfmt_misc/qemu-$options->{qemu}";
-                    while (my $line = <$fh>) {
-                        chomp($line);
-                        if ($line =~ /^flags: [A-Z]*F[A-Z]*$/) {
-                            $require_qemu_static = 0;
-                            last;
-                        }
-                    }
-                    close $fh;
-                }
-            };
-            if ($require_qemu_static) {
-                # other modes require a static qemu-user binary
-                my $qemubin = "/usr/bin/qemu-$options->{qemu}-static";
-                if (!-e $qemubin) {
-                    error "cannot find $qemubin";
-                }
-                copy $qemubin, "$options->{root}/$qemubin"
-                  or error "cannot copy $qemubin: $!";
-                # File::Copy does not retain permissions but on some
-                # platforms (like Travis CI) the binfmt interpreter must
-                # have the executable bit set or otherwise execve will
-                # fail with EACCES
-                chmod 0755, "$options->{root}/$qemubin"
-                  or error "cannot chmod $qemubin: $!";
-            }
-        } else {
-            error "unknown mode: $options->{mode}";
-        }
     }
 
     # some versions of coreutils use the renameat2 system call in mv.