Prepare for rustfmt 2.0

Summary:
Generated by formatting with rustfmt 2.0.0-rc.2 and then a second time with fbsource's current rustfmt (1.4.14).

This results in formatting for which rustfmt 1.4 is idempotent but is closer to the style of rustfmt 2.0, reducing the amount of code that will need to change atomically in that upgrade.

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*Why now?* **:** The 1.x branch is no longer being developed and fixes like rust-lang/rustfmt#4159 (which we need in fbcode) only land to the 2.0 branch.

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Reviewed By: zertosh

Differential Revision: D23568787

fbshipit-source-id: 4f0a79389143369493564dde4233566d3574c86f

rust/watchman_client/src/lib.rs

@@ -64,7 +64,9 @@ use prelude::*;
 pub enum Error {
     #[error("IO Error: {0}")]
     Tokio(#[from] tokio::io::Error),
-    #[error("While invoking the {watchman_path} CLI to discover the server connection details: {reason}, stderr=`{stderr}`")]
+    #[error(
+        "While invoking the {watchman_path} CLI to discover the server connection details: {reason}, stderr=`{stderr}`"
+    )]
     ConnectionDiscovery {
         watchman_path: PathBuf,
         reason: String,