The new oldtest directory is in test/old/testdir. The reason for this is
that many tests have hardcoded the parent directory name to be
'testdir'.

Problem:    Failure to compile a pattern not tested much.
Solution:   Add tests where a pattern fails to compile. (Yegappan Lakshmanan,
            closes vim/vim#7004)

https://github.com/vim/vim/commit/531be47ac5522807b265c6287021a01c9b895ac9

* Revert "oldtests: win: shellslash for cdpath,tags,:find"

This reverts commit 6245b4873d5e24fade9aadadf32645bfb3ebfc31.

* Revert "oldtests: set shellslash for ":cd" test"

This reverts commit eba1ebafe554fcf6dcd8c933f53b43ca9c5b3b6a.

* Revert "oldtests: set shellslash in Test_shellescape()"

This reverts commit e428fc4b52d986fec0d544e371b05e8c7e18db93.

* Revert "fixup! vim-patch:8.0.1782: no simple way to label quickfix entries"

This reverts commit ac1fbc28601a05cdca19f868449c86b8dd70328c.

* Revert "test/old: pass Test_statusline on Windows"

This reverts commit 6efa3bff09afb0e54ad71278ac60259bf41be286.

* Revert "oldtests: set shellslash for Test_non_zero_arg"

This reverts commit 42e1e2495cc51f659d505bfec8b72905c19e4094.

* Revert "oldtests: set shellslash in Test_true_false_arg()"

This reverts commit 8bd194f98aaf8d79886b78f4bd29f9525c1459c8.

* Remove unnecessary set shellslash

Since #10679 no longer requires individual set shellslash, it is removed.


Co-Authored-By: erw7 <erw7.github@gmail.com>

Problem:    Test17 is old style.
Solution:   Turn into new style test. (Yegappan Lakshmanan, closes vim/vim#4347)
https://github.com/vim/vim/commit/f0ab01f6d868164ed0bb247b6f7b152e6929ef18