fix: remote oh-my-zsh env var export issue (topgrade-rs#528)

* fix: fix remove oh-my-zsh env export issue

src/steps/zsh.rs

@@ -181,10 +181,17 @@ pub fn run_oh_my_zsh(ctx: &ExecutionContext) -> Result<()> {
  .args([
  "-c",
  // ` > /dev/null` is used in case the user's zshrc will have some stdout output.
- format!("source {} > /dev/null && echo $ZSH", zshrc_path.display()).as_str(),
+ format!(
+ "source {} > /dev/null && export -p | grep ZSH > /dev/null && echo $ZSH",
+ zshrc_path.display()
+ )
+ .as_str(),
  ])
  .output_checked_utf8()?;
- env::set_var("ZSH", output.stdout.trim());
+ let zsh_env = output.stdout.trim();
+ if !zsh_env.is_empty() {
+ env::set_var("ZSH", zsh_env);
+ }
  }
 
  let oh_my_zsh = env::var("ZSH")