Please don't. I'm running an NFSv4.1 environment with sec=krb5p and autofs-ldap just fine without this.
The rpc.idmapd(8) man page says among other things: "Note that on more recent kernels only the NFSv4 server uses rpc.idmapd. The NFSv4 client instead uses nfsidmap(8), and only falls back to rpc.idmapd if there was a problem running the nfsidmap(8) program." (Aside: the libnfsidmap2 package mistakenly has the nfsidmap man page in section 5 rather than 8, in both stretch and buster (I haven't checked sid). Minor documentation bug.) This applies to Debian stretch and later. I'm not starting rpc.idmapd on client-only machines at all (the nfsidmap mechanism works for me) and home directories are reliably being automounted. This makes me believe that your proposed "fix" is incorrect (at least for general use; if you need to run an old/odd kernel you may need something like this, but then you should fix it locally in /etc/systemd/system/ and not impose it on everyone else). >From reading #842199 I get the impression that autofs is starting too soon, before the LDAP server can be reached. On my systems autofs.service has an effective After=nslcd.service which seems to be generated on the basis of an # X-Start-Before: autofs comment in /etc/init.d/nslcd (so you probably won't have this on systems without nslcd). There are many ways to influence the order in which systemd starts services; why pick on rpc.idmapd?
