Add comment on known restrictions of the current implementation.


git-svn-id: https://llvm.org/svn/llvm-project/llvdb/trunk@137748 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/redo.py b/test/redo.py
index 2518f07..b924c4c 100755
--- a/test/redo.py
+++ b/test/redo.py
@@ -23,7 +23,14 @@
 
 # To be filled with the filterspecs found in the session logs.
 redo_specs = []
+
+# There is a known bug with respect to comp_specs and arch_specs, in that if we
+# encountered "-C clang" and "-C gcc" when visiting the session files, both
+# compilers will end up in the invocation of the test driver when rerunning.
+# That is: ./dotest -v -C clang^gcc ... -f ...".  Ditto for "-A" flags.
+# The "-C compiler" for comp_specs.
 comp_specs = set()
+# The "-A arch" for arch_specs.
 arch_specs = set()
 
 def usage():