Revert quoting change in previous commit; adjust test to match code

Revert back to original quoting style used before previous commit.
Adjust init.bats to reflect changes for successful tests.

libexec/rbenv-init

@@ -86,7 +86,7 @@ mkdir -p "${RBENV_ROOT}/"{shims,versions}
 
 case "$shell" in
 fish )
-  echo 9;set -gx PATH '${RBENV_ROOT}'/shims $PATH';
+  echo 4;set -gx PATH '${RBENV_ROOT}/shims' \$PATH";
   echo "set -gx RBENV_SHELL $shell"
 ;;
 * )

test/init.bats

@@ -73,7 +73,7 @@ OUT
   export PATH="${BATS_TEST_DIRNAME}/../libexec:/usr/bin:/bin:/usr/local/bin"
   run rbenv-init - fish
   assert_success
-  assert_line 0 "setenv PATH '${RBENV_ROOT}/shims' \$PATH"
+  assert_line 0 "set -gx PATH '${RBENV_ROOT}/shims' \$PATH"
 }
 
 @test "can add shims to PATH more than once" {
@@ -87,7 +87,7 @@ OUT
   export PATH="${RBENV_ROOT}/shims:$PATH"
   run rbenv-init - fish
   assert_success
-  assert_line 0 "setenv PATH '${RBENV_ROOT}/shims' \$PATH"
+  assert_line 0 "set -gx PATH '${RBENV_ROOT}/shims' \$PATH"
 }
 
 @test "outputs sh-compatible syntax" {