Do not use /home but /var/home

Otherwise flatpak'ed Buildstream and flatpak'ed Flatpak Builder do not work.

ostreedev/ostree#2086

elements/vm/ostree-config.bst

@@ -21,26 +21,48 @@ config:
       gnome.conf.in >gnome.conf
 
   install-commands:
-  - |
-    mkdir %{install-root}/boot
-    mkdir %{install-root}/efi
-    mkdir %{install-root}/etc
-    mkdir %{install-root}/mnt
-    mkdir %{install-root}/run
-    mkdir %{install-root}/opt
-    mkdir %{install-root}/sys
-    mkdir %{install-root}/tmp
-    mkdir %{install-root}/dev
-    mkdir %{install-root}/proc
+  - mkdir %{install-root}/boot
+  - mkdir %{install-root}/efi
+  - mkdir %{install-root}/etc
+  - mkdir %{install-root}/mnt
+  - mkdir %{install-root}/run
+  - mkdir %{install-root}/opt
+  - mkdir %{install-root}/sys
+  - mkdir %{install-root}/tmp
+  - mkdir %{install-root}/dev
+  - mkdir %{install-root}/proc
 
-  - |
-    mkdir -p "%{install-root}/sysroot"
-    ln -s sysroot/ostree "%{install-root}/ostree"
-    ln -s var/home "%{install-root}/home"
-    ln -s var/roothome "%{install-root}/root"
-    ln -s run/media "%{install-root}/media"
+  - mkdir -p "%{install-root}/sysroot"
+  - ln -s sysroot/ostree "%{install-root}/ostree"
+  - ln -s var/roothome "%{install-root}/root"
+  - ln -s run/media "%{install-root}/media"
 
-  - |
-    install -Dm644 -t "%{install-root}/usr/lib/tmpfiles.d" ostree.conf
-    install -Dm644 *.gpg "%{install-root}/etc/pki/ostree/gnome.gpg"
-    install -Dm644 -t "%{install-root}/etc/ostree/remotes.d" gnome.conf
+  # Though we use /var/home in /etc/passwd and this symlink should
+  # be useless removing this symlink breaks --filesystem=host on
+  # flatpak.
+  - ln -s var/home "%{install-root}/home"
+
+  - install -Dm644 -t "%{install-root}/usr/lib/tmpfiles.d" ostree.conf
+  - install -Dm644 *.gpg "%{install-root}/etc/pki/ostree/gnome.gpg"
+  - install -Dm644 -t "%{install-root}/etc/ostree/remotes.d" gnome.conf
+
+public:
+  bst:
+    integration-commands:
+    # /etc/default/useradd is provided by freedesktop-sdk.bst's
+    # components/shadow.bst. In non OSTree configuration it should
+    # stay /home. So we have to adjust the value of HOME in OSTree
+    # configurations only.
+    #
+    # Even though we have a symlink /home -> var/home, we should not
+    # define home directory. The real root filesystem (which is
+    # /sysroot) is not mounted as recursive shared on OSTree.  When
+    # the home directory in /etc/passwd is defined to use the symlink,
+    # then mounts in home are mounted on this /sysroot instead of
+    # /var.  That means that the mount does not propagate in Flatpak
+    # applications. This breaks Flatpak Builder and BuildStream which
+    # require fuse mounts.
+    - |
+      if [ -f /etc/default/useradd ]; then
+        sed -i 's,HOME=/home,HOME=/var/home,' /etc/default/useradd
+      fi