message: Ignore <tab> in libtest output.
  rust-lang/rust#50387 is changing the output from libtest which affected a few Cargo tests.
diff: @@ -301,7 +301,7 @@ test test_hello ... FAILED
  failures:
  ---- test_hello stdout ----
  -<tab>thread 'test_hello' panicked at 'assertion failed:[..]",
  +[..]thread 'test_hello' panicked at 'assertion failed:[..]",
  )
  .with_stdout_contains("[..]`(left == right)`[..]")
  .with_stdout_contains("[..]left: `\"hello\"`,[..]")
  @@ -367,7 +367,7 @@ test test_hello ... FAILED
  failures:
  ---- test_hello stdout ----
  -<tab>thread 'test_hello' panicked at 'assertion failed: false', \
  +[..]thread 'test_hello' panicked at 'assertion failed: false', \
  tests[/]footest.rs:4[..]
  ",
  )
  @@ -413,7 +413,7 @@ test test_hello ... FAILED
  failures:
  ---- test_hello stdout ----
  -<tab>thread 'test_hello' panicked at 'assertion failed: false', \
  +[..]thread 'test_hello' panicked at 'assertion failed: false', \
  src[/]lib.rs:4[..]
  ",
  )
  