libstore: improve hash mismatch error messages

Use the same output ordering and format everywhere.

This is such a common issue that we trade the single-line error message for
more readability.

Old message:
```
fixed-output derivation produced path '/nix/store/d4nw9x2sy9q3r32f3g5l5h1k833c01vq-example.com' with sha256 hash '08y4734bm2zahw75b16bcmcg587vvyvh0n11gwiyir70divwp1rm' instead of the expected hash '1xzwnipjd54wl8g93vpw6hxnpmdabq0wqywriiwmh7x8k0lvpq5m'
```

New message:
```
hash mismatch in fixed-output derivation '/nix/store/d4nw9x2sy9q3r32f3g5l5h1k833c01vq-example.com':
  wanted: sha256:1xzwnipjd54wl8g93vpw6hxnpmdabq0wqywriiwmh7x8k0lvpq5m
  got:    sha256:08y4734bm2zahw75b16bcmcg587vvyvh0n11gwiyir70divwp1rm

```

1 files changed, 2 insertions, 2 deletions

diff --git a/src/libstore/download.cc b/src/libstore/download.cc
index fef2cf7a388a..467f570bbf05 100644
--- a/src/libstore/download.cc
+++ b/src/libstore/download.cc
@@ -881,8 +881,8 @@ Path Downloader::downloadCached(ref<Store> store, const string & url_, bool unpa
         Hash gotHash = unpack
             ? hashPath(expectedHash.type, store->toRealPath(storePath)).first
             : hashFile(expectedHash.type, store->toRealPath(storePath));
-        throw nix::Error("hash mismatch in file downloaded from '%s': got hash '%s' instead of the expected hash '%s'",
-            url, gotHash.to_string(), expectedHash.to_string());
+        throw nix::Error("hash mismatch in file downloaded from '%s':\n  wanted: %s\n  got:    %s",
+            url, expectedHash.to_string(), gotHash.to_string());
     }
 
     return store->toRealPath(storePath);