clang-format: Fix bug in wrapping behavior of operators.

Before (even violating the column limit):
  auto Diag =
      diag()
      << aaaaaaaaaaaaaaaa(aaaaaaaaaaaa, aaaaaaaaaaaaa, aaaaaaaaaaaaaaaaaaaaaaaaaa);

After:
  auto Diag = diag() << aaaaaaaaaaaaaaaa(aaaaaaaaaaaa, aaaaaaaaaaaaa,
                                         aaaaaaaaaaaaaaaaaaaaaaaaaa);

llvm-svn: 297931
diff --git a/clang/lib/Format/ContinuationIndenter.cpp b/clang/lib/Format/ContinuationIndenter.cpp
index c518db8..5ae8839 100644
--- a/clang/lib/Format/ContinuationIndenter.cpp
+++ b/clang/lib/Format/ContinuationIndenter.cpp
@@ -915,6 +915,7 @@
        I != E; ++I) {
     ParenState NewParenState = State.Stack.back();
     NewParenState.ContainsLineBreak = false;
+    NewParenState.LastOperatorWrapped = true;
     NewParenState.NoLineBreak =
         NewParenState.NoLineBreak || State.Stack.back().NoLineBreakInOperand;