rustfmt: rustfmt fails with errors "left behind trailing whitespace"

I have rustfmt-preview installed on the nightly toolchain (rustc 1.30.0-nightly (3edb355b7 2018-08-03)) using rustup.

Running cargo +nightly fmt on the crate: https://github.com/frankmcsherry/differential-dataflow results in numerous “left behind trailing whitespace” errors. Some sample errors:

internal error: left behind trailing whitespace
  --> [..]/differential-dataflow/src/algorithms/prefix_sum.rs:70
   |
70 |         .iterate(|ranges| 
   |                          ^
warning: rustfmt may have failed to format. See previous 1 errors.

  --> [..]/differential-dataflow/examples/seb.rs:37
   |
37 |       let cooccurrences = 
   |                          ^
  --> [..]/differential-dataflow/examples/seb.rs:44
   |
44 |       let row_sums = 
   |                     ^

  --> [..]/differential-dataflow/examples/dataflow.rs:35
   |
35 |             let (tweet_input, tweets) = scope.new_collection(); 
   |                                                                ^