patch 8.2.3719: MS-Windows: test sometimes runs into existing swap file

Problem:    MS-Windows: test sometimes runs into existing swap file.
Solution:   Use a different file name.
diff --git a/src/testdir/test_buffer.vim b/src/testdir/test_buffer.vim
index aa2fe7a..0d87138 100644
--- a/src/testdir/test_buffer.vim
+++ b/src/testdir/test_buffer.vim
@@ -389,12 +389,12 @@
   set noshellslash
   %bwipe!
   let bufnames = [
-    \ #{id: 'b0', name: 'test://xyz/foo/b0'    , match: 1},
-    \ #{id: 'b1', name: 'test+abc://xyz/foo/b1', match: 0},
-    \ #{id: 'b2', name: 'test_abc://xyz/foo/b2', match: 0},
-    \ #{id: 'b3', name: 'test-abc://xyz/foo/b3', match: 1},
-    \ #{id: 'b4', name: '-test://xyz/foo/b4'   , match: 0},
-    \ #{id: 'b5', name: 'test-://xyz/foo/b5'   , match: 0},
+    \ #{id: 'ssb0', name: 'test://xyz/foo/ssb0'    , match: 1},
+    \ #{id: 'ssb1', name: 'test+abc://xyz/foo/ssb1', match: 0},
+    \ #{id: 'ssb2', name: 'test_abc://xyz/foo/ssb2', match: 0},
+    \ #{id: 'ssb3', name: 'test-abc://xyz/foo/ssb3', match: 1},
+    \ #{id: 'ssb4', name: '-test://xyz/foo/ssb4'   , match: 0},
+    \ #{id: 'ssb5', name: 'test-://xyz/foo/ssb5'   , match: 0},
     \]
   for buf in bufnames
     new `=buf.name`