t: use sane_unset instead of unset

Change several tests to use the sane_unset function introduced in
v1.7.3.1-35-g00648ba instead of the built-in unset function.

This fixes a failure I was having on t9130-git-svn-authors-file.sh on
Solaris, and prevents several other issues from occurring.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/t/t4150-am.sh b/t/t4150-am.sh
index d7d9ccc..7e6e59a 100755
--- a/t/t4150-am.sh
+++ b/t/t4150-am.sh
@@ -136,7 +136,7 @@
 	git format-patch -M --stdout lorem^ >rename-add.patch &&
 
 	# reset time
-	unset test_tick &&
+	sane_unset test_tick &&
 	test_tick
 '
 
diff --git a/t/t5560-http-backend-noserver.sh b/t/t5560-http-backend-noserver.sh
index 0ad7ce0..ef98d95 100755
--- a/t/t5560-http-backend-noserver.sh
+++ b/t/t5560-http-backend-noserver.sh
@@ -17,7 +17,7 @@
 GET() {
 	REQUEST_METHOD="GET" && export REQUEST_METHOD &&
 	run_backend "/repo.git/$1" &&
-	unset REQUEST_METHOD &&
+	sane_unset REQUEST_METHOD &&
 	if ! grep "Status" act.out >act
 	then
 		printf "Status: 200 OK\r\n" >act
@@ -30,8 +30,8 @@
 	REQUEST_METHOD="POST" && export REQUEST_METHOD &&
 	CONTENT_TYPE="application/x-$1-request" && export CONTENT_TYPE &&
 	run_backend "/repo.git/$1" "$2" &&
-	unset REQUEST_METHOD &&
-	unset CONTENT_TYPE &&
+	sane_unset REQUEST_METHOD &&
+	sane_unset CONTENT_TYPE &&
 	if ! grep "Status" act.out >act
 	then
 		printf "Status: 200 OK\r\n" >act
diff --git a/t/t6032-merge-large-rename.sh b/t/t6032-merge-large-rename.sh
index fdb6c25..94f010b 100755
--- a/t/t6032-merge-large-rename.sh
+++ b/t/t6032-merge-large-rename.sh
@@ -95,7 +95,7 @@
 '
 
 test_expect_success 'massive simple rename does not spam added files' '
-	unset GIT_MERGE_VERBOSITY &&
+	sane_unset GIT_MERGE_VERBOSITY &&
 	git merge --no-stat simple-rename | grep -v Removing >output &&
 	test 5 -gt "$(wc -l < output)"
 '
diff --git a/t/t9130-git-svn-authors-file.sh b/t/t9130-git-svn-authors-file.sh
index b324c49..c3443ce 100755
--- a/t/t9130-git-svn-authors-file.sh
+++ b/t/t9130-git-svn-authors-file.sh
@@ -96,8 +96,8 @@
 		rm -r "$GIT_DIR" &&
 		test x = x"$(git config svn.authorsfile)" &&
 		test_config="$HOME"/.gitconfig &&
-		unset GIT_DIR &&
-		unset GIT_CONFIG &&
+		sane_unset GIT_DIR &&
+		sane_unset GIT_CONFIG &&
 		git config --global \
 		  svn.authorsfile "$HOME"/svn-authors &&
 		test x"$HOME"/svn-authors = x"$(git config svn.authorsfile)" &&
diff --git a/t/t9200-git-cvsexportcommit.sh b/t/t9200-git-cvsexportcommit.sh
index 518358a..b59be9a 100755
--- a/t/t9200-git-cvsexportcommit.sh
+++ b/t/t9200-git-cvsexportcommit.sh
@@ -321,7 +321,7 @@
 
 	(mkdir shared &&
 	 cd shared &&
-	 unset GIT_DIR &&
+	 sane_unset GIT_DIR &&
 	 cvs co . &&
 	 git init &&
 	 git add " space" &&
diff --git a/t/t9808-git-p4-chdir.sh b/t/t9808-git-p4-chdir.sh
index eb8cc95..f002283 100755
--- a/t/t9808-git-p4-chdir.sh
+++ b/t/t9808-git-p4-chdir.sh
@@ -25,7 +25,7 @@
 	test_when_finished cleanup_git &&
 	(
 		P4CONFIG=p4config && export P4CONFIG &&
-		unset P4PORT P4CLIENT &&
+		sane_unset P4PORT P4CLIENT &&
 		"$GITP4" clone --verbose --dest="$git" //depot
 	)
 '
@@ -37,7 +37,7 @@
 	test_when_finished cleanup_git &&
 	(
 		P4CONFIG=p4config && export P4CONFIG &&
-		unset P4PORT P4CLIENT &&
+		sane_unset P4PORT P4CLIENT &&
 		"$GITP4" clone --verbose --dest="git" //depot
 	)
 '