regress test tweaks

src/cmd/ksh93/tests/builtins.sh:
- Fix a test so it doesn't fail if 'whence -a' finds multiple paths
  for 'ls'.

src/cmd/ksh93/tests/coprocess.sh
- Update known failure comment with current information.

src/cmd/ksh93/tests/builtins.sh

@@ -838,7 +838,7 @@ actual=$(FPATH=$tmp; ls /dev/null; whence -a ls >/dev/null; ls /dev/null)
 expect="ls is an alias for 'echo ALL UR F1LEZ R G0N3'
 ls is a tracked alias for ${ whence -p ls; }"
 actual=$(hash -r; alias ls='echo ALL UR F1LEZ R G0N3'; hash ls; whence -a ls)
-[[ $actual == "$expect" ]] || err_exit "'whence -a' does not report tracked alias if alias exists" \
+[[ $actual == "$expect" || $actual == "$expect"$'\n'* ]] || err_exit "'whence -a' does not report tracked alias if alias exists" \
 	"(expected $(printf %q "$expect"), got $(printf %q "$actual"))"
 
 # 'whence -f' should ignore functions

src/cmd/ksh93/tests/coprocess.sh

@@ -224,8 +224,8 @@ do
 	trap - TERM
 	[[ $sleep_pid ]] && kill $sleep_pid
 	
-# TODO: The /bin/cat iteration of this test is known to hang intermittently.
-# See: https://github.com/ksh93/ksh/issues/132
+# TODO: The /bin/cat iteration of this test is known to hang intermittently on Debian and
+# derived systems (such as Ubuntu). See: https://github.com/ksh93/ksh/issues/132
 # It is temporarily disabled here to avoid Github CI failures due to this known issue
 # while we work on other things. Export DEBUG_COPROCESS to include it in the tests.
 if [[ $cat != "$bincat" || -v DEBUG_COPROCESS ]]; then