fix(os): Stop pacman from doing it's CheckSpace on ZFS (#3)

setup.sh

@@ -237,8 +237,20 @@ function pacman_dl_parallel () {
     sed -ri -e 's'$'\x1''^.*?(ParallelDownloads)[^\r\n\f]*'$'\x1''\1 = 5'$'\x1''g' '/etc/pacman.conf'
 }
 
+function pacman_dont_check_space () {
+    # See pacman bug comment
+    # https://bugs.archlinux.org/task/45070#comment142712
+    # 
+    # When we pacstrap onto ZFS pacman incorrectly calculates and
+    # overestimates required disk space. We instead assume an installation
+    # gets done with at least a 10 GiB drive which is plenty. Skip pacman's
+    # size check.
+    sed -ri -e 's'$'\x1''^.*?(CheckSpace)([^\r\n\f]*)'$'\x1''#\1\2'$'\x1''g' '/etc/pacman.conf'
+}
+
 function install_archlinux () {
     pacman_dl_parallel
+    pacman_dont_check_space
     pacstrap /mnt              \
         base                   \
         base-devel             \