[v3,2/2] timezone: test-case for BZ #28707

diff --git a/timezone/Makefile b/timezone/Makefile
index c624a189b322..f091663b8bbb 100644
--- a/timezone/Makefile
+++ b/timezone/Makefile
@@ -23,7 +23,7 @@  subdir	:= timezone
 include ../Makeconfig
 
 others	:= zdump zic
-tests	:= test-tz tst-timezone tst-tzset
+tests	:= test-tz tst-timezone tst-tzset tst-bz28707
 
 generated-dirs += testdata
 
@@ -85,10 +85,12 @@  $(objpfx)tst-timezone.out: $(addprefix $(testdata)/, \
 				       America/Sao_Paulo Asia/Tokyo \
 				       Europe/London)
 $(objpfx)tst-tzset.out: $(addprefix $(testdata)/XT, 1 2 3 4)
+$(objpfx)tst-bz28707.out: $(testdata)/XT5
 
 test-tz-ENV = TZDIR=$(testdata)
 tst-timezone-ENV = TZDIR=$(testdata)
 tst-tzset-ENV = TZDIR=$(testdata)
+tst-bz28707-ENV = TZDIR=$(testdata)
 
 # Note this must come second in the deps list for $(built-program-cmd) to work.
 zic-deps = $(objpfx)zic $(leapseconds) yearistype
@@ -122,6 +124,10 @@  $(testdata)/XT%: testdata/XT%
 	$(make-target-directory)
 	cp $< $@
 
+$(testdata)/XT%: testdata/gen-XT%.sh
+	$(SHELL) $< > $@.tmp
+	mv $@.tmp $@
+
 $(objpfx)tzselect: tzselect.ksh $(common-objpfx)config.make
 	sed -e 's|TZDIR=[^}]*|TZDIR=$(zonedir)|' \
 	    -e '/TZVERSION=/s|see_Makefile|"$(version)"|' \
diff --git a/timezone/testdata/gen-XT5.sh b/timezone/testdata/gen-XT5.sh
new file mode 100755
index 000000000000..3cea0569eb5a
--- /dev/null
+++ b/timezone/testdata/gen-XT5.sh
@@ -0,0 +1,16 @@ 
+#! /bin/sh
+
+# This test-case is the tzfile for America/Asuncion
+# generated by tzlib-2021e as follows, using the tzlib-2021e
+# zic: "zic -d DEST -r @1546300800 -L /dev/null -b slim
+# SOURCE/southamerica".  Note that in its type 2 header, it
+# has two entries in its "time-types" array (types), but
+# only one entry in its "transition types" array
+# (type_idxs).
+
+printf \
+'TZif2\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0'\
+'\0\0\0\0\0\0\0\1\0\0\0\1\0\0\0\0\0\0\0TZif2\0\0\0\0\0\0\0\0'\
+'\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\1\0\0\0\2\0\0\0\b\0'\
+'\0\0\0\*\255\200\1\0\0\0\0\0\0\377\377\325\320\1\4-00\0-03\0\n'\
+'<-04>4<-03>,M10.1.0/0,M3.4.0/0\n'
diff --git a/timezone/tst-bz28707.c b/timezone/tst-bz28707.c
new file mode 100644
index 000000000000..0a9df1e9a094
--- /dev/null
+++ b/timezone/tst-bz28707.c
@@ -0,0 +1,46 @@ 
+/* Copyright (C) 2021 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <time.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+/* Test that we can use a truncated timezone-file, where the time-type
+   at index 0 is not indexed by the transition-types array (and the
+   transition-types array does not contain at least both one DST and one
+   normal time members).  */
+
+static int
+do_test (void)
+{
+  if (setenv ("TZ", "XT5", 1))
+    {
+      puts ("setenv failed.");
+      return 1;
+    }
+
+  tzset ();
+
+  return
+    /* Sanity-check that we got the right timezone-name for DST.  For
+       normal time, we're likely to get "-00" (the "unspecified" marker),
+       even though the POSIX timezone string says "-04".  Let's not test
+       that.  */
+    !(strcmp (tzname[1], "-03") == 0);
+}
+#include <support/test-driver.c>