legacy tests: migrate test54

src/nvim/testdir/test54.in

@@ -1,22 +0,0 @@
-Some tests for buffer-local autocommands
-
-STARTTEST
-:so small.vim
-:e xx
-:if has("vms")
-: !del test.out.*
-: au BufLeave <buffer> :!write sys$output "buffer-local autommand in %" > test.out
-:else
-: !rm -f test.out
-: au BufLeave <buffer> :!echo buffer-local autommand in %>> test.out
-:endif
-:e somefile           " here, autocommand for xx shall write test.out 
-:                     " but autocommand shall not apply to buffer named <buffer>
-:bwipe xx             " here, autocommand shall be auto-deleted
-:e xx                 " nothing shall be written
-:e somefile           " nothing shall be written
-:qa!
-ENDTEST
-
-start of test file xx
-end of test file xx

src/nvim/testdir/test54.ok

@@ -1 +0,0 @@
-buffer-local autommand in xx