Safer copying of nested git repositories when comparing changes

Sometimes Claude Code finds a git repository nested inside the folder it is working in. To compare that repository's changes, it makes a temporary copy. That copy step now has more checks:

• It refuses if the repository's working folder (its work tree, the folder git treats as holding the files) is not the folder Claude Code was checking.
• It reads git's configuration with GIT_DIR pointed at a repository that does not exist and starting from the top of the filesystem, so no surrounding repository's settings are picked up.
• It runs an extra check on the temporary copy before using it.
• It creates the temporary folder in a new way.

When a configuration value is rejected, the message now labels it as a "config value of" that setting.