Merge branch 'jk/test-z-n-unquoted'

t9xxx series has been updated primarily for readability, while
fixing small bugs in it.  A few scripted Porcelains have also been
updated to fix possible bugs around their use of "test -z" and
"test -n".

* jk/test-z-n-unquoted:
  always quote shell arguments to test -z/-n
  t9103: modernize test style
  t9107: switch inverted single/double quotes in test
  t9107: use "return 1" instead of "exit 1"
  t9100,t3419: enclose all test code in single-quotes
  t/lib-git-svn: drop $remote_git_svn and $git_svn_id

git-rebase--interactive.sh

@@ -867,12 +867,12 @@ add_exec_commands () {
 # $3: the input filename
 check_commit_sha () {
 	badsha=0
-	if test -z $1
+	if test -z "$1"
 	then
 		badsha=1
 	else
 		sha1_verif="$(git rev-parse --verify --quiet $1^{commit})"
-		if test -z $sha1_verif
+		if test -z "$sha1_verif"
 		then
 			badsha=1
 		fi