chore: Update rustfmt

.travis.yml

@@ -14,13 +14,12 @@ matrix:
       cargo +nightly-2017-10-09 install clippy --vers "$CLIPPY_VERS" --force || true
     script: |
       cargo +nightly-2017-10-09 clippy -- -D warnings
-  - rust: nightly-2017-10-09
-    env: RUSTFMT_VERS="0.2.8"
-    before_script: |
-      [[ "$(cargo +nightly-2017-10-09 fmt -- --version)" != "$RUSTFMT_VERS"* ]] && \
-      cargo +nightly-2017-10-09 install rustfmt-nightly --vers "$RUSTFMT_VERS" --force || true
-    script: |
-      cargo +nightly-2017-10-09 fmt --all -- --write-mode=diff
+  - rust: 1.24.0  # `stable`: Locking down for consistent behavior
+    env: RUSTFMT
+    install:
+    - rustup component add rustfmt-preview
+    script:
+    - cargo fmt -- --write-mode=diff
 before_script:
 - |
   pip install 'travis-cargo<0.2' --user &&

src/output.rs

@@ -6,7 +6,6 @@ use std::fmt;
 use std::process;
 use std::rc;
 
-
 #[derive(Clone, PartialEq, Eq)]
 pub enum Content {
     Str(String),