CHECK-EMPTY: one edge case and recommendations

[stanislaw]

Check file:

CHECK: String1
CHECK-EMPTY:
CHECK: String2

Test:

echo -e "String1\nString2" | (/Users/Stanislaw/workspace/inbox-active-code/FileCheck.py/tests/integration/tools/FileCheck/FileCheck /Users/Stanislaw/workspace/inbox-active-code/FileCheck.py/tests/integration/tests/examples/check-commands/CHECK-EMPTY/Failure/CHECK-EMPTY.check 2>&1; test $? = 1)
/Users/Stanislaw/workspace/inbox-active-code/FileCheck.py/tests/integration/tools/FileCheck
/Users/Stanislaw/workspace/inbox-active-code/FileCheck.py/tests/integration/tests/examples/check-commands/CHECK-EMPTY/Failure/CHECK-EMPTY.check:2:13: error: CHECK-EMPTY: is not on the line after the previous match
CHECK-EMPTY:
            ^
<stdin>:3:1: note: 'next' match was here

^
<stdin>:1:8: note: previous match ended here
String1
       ^
<stdin>:2:1: note: non-matching line after previous match is here
String2
^

What is weird is that according to the output of the LLVM's FileCheck, the line #3 exists in the input, while

echo -e "String1\nString2" | wc -l
2

P.S. If this is resolved somehow, the CHECK-EMPTY.itest-py has to be made just .itest.