--- src/sanity.sh	Sat Oct 22 15:35:07 2016
+++ src/sanity.sh	Sat Oct 22 15:40:12 2016
@@ -1,5 +1,7 @@
 #! /bin/sh
 :
+# $MirOS: src/gnu/usr.bin/cvs/src/sanity.sh,v 1.4 2016/10/22 15:40:12 tg Exp $
+#-
 # set DISABLE_ANY_RSH=1 to skip rsh and ssh calls
 #
 #	sanity.sh -- a growing testsuite for cvs.
@@ -92,6 +94,23 @@ checklongoptarg()
     fi
 }
 
+do_save_TZ()
+{
+	saveset_TZ=${TZ+false}
+	save_TZ=$TZ
+	TZ=UTC0; export TZ
+}
+
+do_restore_TZ()
+{
+	if $saveset_TZ :; then
+		unset TZ
+	else
+		TZ=$save_TZ
+		export TZ
+	fi
+}
+
 # See TODO list at end of file.
 
 # required to make this script work properly.
@@ -9376,8 +9395,7 @@ add
 	  # Also the -d option.
 
 	  # Set a predictable time zone for these tests.
-	  save_TZ=$TZ
-	  TZ=UTC0; export TZ
+	  do_save_TZ
 
 	  mkdir 1; cd 1
 	  mkdir adir bdir cdir
@@ -9500,7 +9518,7 @@ import-it
 	  dotest_fail importc-12 "test -d ${TESTDIR}/other" ""
 
 	  dokeep
-	  TZ=$save_TZ
+	  do_restore_TZ
 	  cd ..
 	  rm -r 1 2
 	  modify_repo rm -rf $CVSROOT_DIRNAME/first-dir
@@ -22119,8 +22137,7 @@ ${SPROG} update: Updating crerepos-dir"
 
 	  # Save the timezone and set it to UTC for these tests to make the
 	  # value more predicatable.
-	  save_TZ=$TZ
-	  TZ=UTC0; export TZ
+	  do_save_TZ
 
 	  modify_repo mkdir $CVSROOT_DIRNAME/first-dir
 
@@ -22597,7 +22614,7 @@ revision 1\.5
 revision 1\.4"
 
 	  dokeep
-	  TZ=$save_TZ
+	  do_restore_TZ
 	  cd ..
 	  rm -r first-dir
 	  modify_repo rm -rf $CVSROOT_DIRNAME/first-dir
@@ -22787,8 +22804,7 @@ EOF
 	  # revisions 1.1 and 1.1.1.1 differ by 1 second.
 
 	  # Need a predictable time zone.
-	  save_TZ=$TZ
-	  TZ=UTC0; export TZ
+	  do_save_TZ
 
           mkdir rcs4
           cd rcs4
@@ -22846,7 +22862,7 @@ File: file1            	Status: Up-to-da
    Sticky Options:	(none)'
 
 	  dokeep
-	  TZ=$save_TZ
+	  do_restore_TZ
 	  cd ../..
           rm -r rcs4
           modify_repo rm -rf $CVSROOT_DIRNAME/rcs4-dir
@@ -25438,8 +25454,7 @@ done"
 	  #		for checkout and update as well.
 	  #
 	  mkdir 1; cd 1
-	  save_TZ=$TZ
-	  TZ=UTC0; export TZ
+	  do_save_TZ
 	  dotest tagdate-1 "${testcvs} -q co -l ." ''
 	  mkdir first-dir
 	  dotest tagdate-2 "${testcvs} add first-dir" \
@@ -25903,7 +25918,7 @@ File: file3            	Status: Up-to-da
 
 	  unset date_T1 date_T2 date_T3 date_T4 date_T5
 	  unset date_T6 date_T7 date_T8 date_T9
-	  TZ=$save_TZ
+	  do_restore_TZ
 
 	  dokeep
 	  rm -r 1 2 3 4