Fix patch command to apply with git inside another repository

ⓘ When GNU patch is not installed, git apply was run inside the module directory, and if the Webmin root itself was a git repository, git resolved paths relative to that root and silently skipped the patched files.

Limit repository discovery to the current directory and allow reduced context, similar to the default fuzz used by patch, so slightly drifted context lines no longer cause a rejection.

bin/patch

@@ -163,7 +163,14 @@ elsif (has_command('patch')) {
 	}
 # Apply patch using git command
 else {
-	$output = `$cmd 2>&1 | git apply --reject --verbose --whitespace=fix 2>&1`;
+	# If the current directory is inside some git repository (e.g. Webmin
+	# root tracked with git), git would treat patch paths as relative to
+	# that repository root and silently skip them, so stop repository
+	# discovery at the parent directory to always apply patch paths
+	# relative to the current directory
+	local $ENV{'GIT_CEILING_DIRECTORIES'} = dirname(cwd());
+	# Allow reduced context, similar to the default fuzz used by patch
+	$output = `$cmd 2>&1 | git apply --reject --verbose -C1 --whitespace=fix 2>&1`;
 	if ($output !~ /applied patch.*?cleanly/i) {
 		print "Patch failed: $output\n";
 		exit 1;