This is in today's (2012.07.01) git-head, and previous versions, too.
If there is an escaped backslash at the end of a string then ivlpp does not skip it properly to end the string on the subsequent double quote. Attached is a test case which ivlpp does not preprocess correctly.
Adding "<CSTRING>\\\\ |" before "<CSTRING>\\\" |" near line 263 in ivlpp/lexor.lex makes ivlpp properly skip escaped backslashes. The lexer for ivl already has this construct, so no problem shows up there.