zsh prompt: check whether inside git repository and not being ignored by git

In my zsh shell, I am dynamically changing prompt depending on whether I am inside git repository or not. I am using following git command to check: if $(git rev-parse --is-inside-work-tree >/dev/null 2>&1); then ... now I also want to distinguish whether current directory is being ignored by git. So I have added one more check to my if statement: if $(git rev-parse --is-inside-work-tree >/dev/null 2>&1) && ! $(git check-ignore . >/dev/null 2>&1); then ... This works fine, but I was wondering whether I could simplify this into one git command. Since the prompt is refreshed on every ENTER, it tends to slow down the shell noticeably on some slower machines. UPDATE ====== The accepted solution from @Stephen Kitt works great, except in following situation: I am using repository across filesystems. Lets say git resides at /.git (because I want to track my config files in /etc), but I also want to track some files in /var/foo, which is a different partition/filesystem. When I am located at / and execute following command, everything works as expected, and I get return code 1 (because /var/foo is being tracked): # git check-ignore -q /var/foo But when I am located anywhere in /var, the same command fails with error code 128 and following error message: # git check-ignore -q /var/foo fatal: not a git repository (or any parent up to mount point /) Stopping at filesystem boundary (GIT_DISCOVERY_ACROSS_FILESYSTEM not set). But I think this is only problem with the check-ignore command. Otherwise git seems to work fine across filesystem. I can track files in /var/foo fine. The expected behavior should be that git check-ignore -q /var/foo returns 1, and git check-ignore -q /var/bar returns 0, if it is not being tracked. **how can I fix this problem?**