install-yarn: Use test -ef in case /srv is a symlink.

Signed-off-by: Anders Kaseorg <anders@zulip.com>

puppet/zulip_ops/manifests/profile/postgresql.pp

@@ -31,7 +31,7 @@ class zulip_ops::profile::postgresql {
   exec { 'setup_disks':
     command => '/root/setup_disks.sh',
     require => Package["postgresql-${zulip::postgresql_common::version}", 'xfsprogs'],
-    unless  => 'test $(readlink /var/lib/postgresql) = "/srv/postgresql/" -a -d /srv/postgresql',
+    unless  => 'test /var/lib/postgresql/ -ef /srv/postgresql/',
   }
 
   file { "${zulip::postgresql_base::postgresql_confdir}/pg_hba.conf":

scripts/lib/install-yarn

@@ -9,8 +9,7 @@ check_version() {
     # Reading the version of Yarn from its package.json is much faster
     # than running yarn --version.
     link="$(command -v yarn)" \
-        && bin="$(readlink -f "$link")" \
-        && [ "$bin" = /srv/zulip-yarn/bin/yarn ] \
+        && [ "$link" -ef /srv/zulip-yarn/bin/yarn ] \
         && current_version="$(jq -r '.version' /srv/zulip-yarn/package.json)" \
         && [ "$current_version" = "$version" ]
 }