Fix formatting of blob used to shard target cache

The ToJson method of RemoteAddress was wrongly creating a list
instead of a simple string, thus a wrongly formatted backend
description was being used to shard the target cache. This however
does not affect the correctness of the build.

Changelog also updated accordingly.

2 files changed, 8 insertions, 2 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 66406237..107d34f9 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -58,6 +58,12 @@ A feature release on top of `1.2.0`, backwards compatible.
   directories if they are part of the action's input.
 - Fixed overwrite of existing symlinks in the output directory
   when using subcommands `install` and `install-cas`.
+- The format for target-cache shards was changed to a canonical form.
+  The new and old formats do not overlap, therefore the correctness
+  of the builds is not affected. In particular, no special care has
+  to be taken on upgrading or downgrading. However, some target-level
+  cache entries will not be used leading potentially to rebuilding of
+  some targets.
 
 ## Release `1.2.0` (2023-08-25)
 
diff --git a/src/buildtool/common/remote/remote_common.hpp b/src/buildtool/common/remote/remote_common.hpp
index ddbd16fb..be440052 100644
--- a/src/buildtool/common/remote/remote_common.hpp
+++ b/src/buildtool/common/remote/remote_common.hpp
@@ -28,8 +28,8 @@ struct ServerAddress {
     Port port{};
 
     [[nodiscard]] auto ToJson() const noexcept -> nlohmann::json {
-        return nlohmann::json{
-            fmt::format("{}:{}", host, static_cast<std::uint16_t>(port))};
+        return nlohmann::json(
+            fmt::format("{}:{}", host, static_cast<std::uint16_t>(port)));
     }
 };