isolate editor env in reword CLI tests

Clear inherited GIT_EDITOR, VISUAL, and EDITOR in the shared test
harness so CLI tests don't pick up the developer's shell settings.

Othewise the test may fail as it tries to open the user editor
under GIT_EDITOR which takes precedence.

Co-authored-by: Sebastian Thiel <sebastian.thiel@icloud.com>

Author: codex

crates/but-testsupport/src/prepare_cmd_env.rs

@@ -54,6 +54,9 @@ fn updates() -> Vec<EnvOp> {
         EnvOp::Remove("GIT_COMMON_DIR"),
         EnvOp::Remove("GIT_ASKPASS"),
         EnvOp::Remove("SSH_ASKPASS"),
+        EnvOp::Remove("GIT_EDITOR"),
+        EnvOp::Remove("VISUAL"),
+        EnvOp::Remove("EDITOR"),
     ]
     .into_iter()
     .chain(

crates/but/tests/but/command/reword.rs

@@ -89,7 +89,7 @@ fn reword_branch_from_editor_trims_trailing_newlines_in_confirmation_output() ->
         "#!/usr/bin/env bash\nprintf 'renamed-branch\\n\\n' > \"$1\"\n",
     );
     env.but("reword branch-to-rename-123")
-        .env("EDITOR", "bash editor.sh")
+        .env("GIT_EDITOR", "bash editor.sh")
         .assert()
         .success()
         .stdout_eq(str![[r#"