The default Shell is $SHELL, else /bin/sh

With no Shell set, pardes ran fish, which a box may not have and a user
may not use. The default is now the user's login shell ($SHELL), else
/bin/sh; an explicit Shell still overrides it. The tests pin their own
shell (snapshots bash, the python suites /bin/sh or bash) and pass with
SHELL unset; the Config report and docs say where the default comes from.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

1 files changed, 2 insertions, 1 deletions

diff --git a/test/output.zig b/test/output.zig
index 419bcca2..f3e61e93 100644
--- a/test/output.zig
+++ b/test/output.zig
@@ -544,10 +544,11 @@ test "Config prints the startup path and refreshes its one output" {
     for ([_][]const u8{
         "Startup config: " ++ path ++ "\n",
         "Theme orchard\n",
-        "Shell requested (new panes) " ++ config.default_shell ++ " (default)\n",
         "Shell effective (last spawn) (none)\n",
         "Shell pending on\n",
     }) |line| try std.testing.expect(std.mem.indexOf(u8, out.content, line) != null);
+    var default_line: [256]u8 = undefined;
+    try std.testing.expect(std.mem.indexOf(u8, out.content, try std.fmt.bufPrint(&default_line, "Shell requested (new panes) {s} (default)\n", .{config.defaultShell()})) != null);
     try std.testing.expectEqualStrings(config.config_buffer, std.fs.path.basename(out.path));
     try std.testing.expectEqual(panes.Output.Origin{ .cmd = .Config }, out.output.?.from);