test/system: Try to handle /etc/resolv.conf on host as absolute symlink

Some Arch Linux hosts have /etc/resolv.conf as an absolute symbolic link
to /run/systemd/resolve/stub-resolv.conf, instead of being a relative
symbolic link to ../run/systemd/resolve/stub-resolv.conf or a regular
file.  eg., the images built by arch-boxes [1].

This changes the target that the Toolbx container's /etc/resolv.conf
points at and confuses the tests [2].

Ideally, these host operating systems should be fixed to use relative
symbolic links.  This is highlighted by skipping the tests, because
there's no point in failing them until that happens.

This is a step towards running the CI on Arch Linux.

[1] https://gitlab.archlinux.org/archlinux/arch-boxes
    https://geo.mirror.pkgbuild.com/images/latest/

[2] Commit 88a95b0
    88a95b07af335be2
    #187

#1438

test/system/203-network.bats

@@ -69,7 +69,13 @@ teardown() {
   run --keep-empty-lines --separate-stderr "$TOOLBX" run readlink /etc/resolv.conf
 
   assert_success
-  assert_line --index 0 "/run/host/etc/resolv.conf"
+
+  if [ "${lines[0]}" = "/run/host/run/systemd/resolve/stub-resolv.conf" ]; then
+    skip "host has absolute symlink"
+  else
+    assert_line --index 0 "/run/host/etc/resolv.conf"
+  fi
+
   assert [ ${#lines[@]} -eq 1 ]
 
   # shellcheck disable=SC2154
@@ -83,7 +89,13 @@ teardown() {
   run --keep-empty-lines --separate-stderr "$TOOLBX" run --distro arch readlink /etc/resolv.conf
 
   assert_success
-  assert_line --index 0 "/run/host/etc/resolv.conf"
+
+  if [ "${lines[0]}" = "/run/host/run/systemd/resolve/stub-resolv.conf" ]; then
+    skip "host has absolute symlink"
+  else
+    assert_line --index 0 "/run/host/etc/resolv.conf"
+  fi
+
   assert [ ${#lines[@]} -eq 1 ]
 
   # shellcheck disable=SC2154
@@ -97,7 +109,13 @@ teardown() {
   run --keep-empty-lines --separate-stderr "$TOOLBX" run --distro fedora --release 34 readlink /etc/resolv.conf
 
   assert_success
-  assert_line --index 0 "/run/host/etc/resolv.conf"
+
+  if [ "${lines[0]}" = "/run/host/run/systemd/resolve/stub-resolv.conf" ]; then
+    skip "host has absolute symlink"
+  else
+    assert_line --index 0 "/run/host/etc/resolv.conf"
+  fi
+
   assert [ ${#lines[@]} -eq 1 ]
 
   # shellcheck disable=SC2154
@@ -111,7 +129,13 @@ teardown() {
   run --keep-empty-lines --separate-stderr "$TOOLBX" run --distro rhel --release 8.10 readlink /etc/resolv.conf
 
   assert_success
-  assert_line --index 0 "/run/host/etc/resolv.conf"
+
+  if [ "${lines[0]}" = "/run/host/run/systemd/resolve/stub-resolv.conf" ]; then
+    skip "host has absolute symlink"
+  else
+    assert_line --index 0 "/run/host/etc/resolv.conf"
+  fi
+
   assert [ ${#lines[@]} -eq 1 ]
 
   # shellcheck disable=SC2154
@@ -125,7 +149,13 @@ teardown() {
   run --keep-empty-lines --separate-stderr "$TOOLBX" run --distro ubuntu --release 16.04 readlink /etc/resolv.conf
 
   assert_success
-  assert_line --index 0 "/run/host/etc/resolv.conf"
+
+  if [ "${lines[0]}" = "/run/host/run/systemd/resolve/stub-resolv.conf" ]; then
+    skip "host has absolute symlink"
+  else
+    assert_line --index 0 "/run/host/etc/resolv.conf"
+  fi
+
   assert [ ${#lines[@]} -eq 1 ]
 
   # shellcheck disable=SC2154
@@ -139,7 +169,13 @@ teardown() {
   run --keep-empty-lines --separate-stderr "$TOOLBX" run --distro ubuntu --release 18.04 readlink /etc/resolv.conf
 
   assert_success
-  assert_line --index 0 "/run/host/etc/resolv.conf"
+
+  if [ "${lines[0]}" = "/run/host/run/systemd/resolve/stub-resolv.conf" ]; then
+    skip "host has absolute symlink"
+  else
+    assert_line --index 0 "/run/host/etc/resolv.conf"
+  fi
+
   assert [ ${#lines[@]} -eq 1 ]
 
   # shellcheck disable=SC2154
@@ -153,7 +189,13 @@ teardown() {
   run --keep-empty-lines --separate-stderr "$TOOLBX" run --distro ubuntu --release 20.04 readlink /etc/resolv.conf
 
   assert_success
-  assert_line --index 0 "/run/host/etc/resolv.conf"
+
+  if [ "${lines[0]}" = "/run/host/run/systemd/resolve/stub-resolv.conf" ]; then
+    skip "host has absolute symlink"
+  else
+    assert_line --index 0 "/run/host/etc/resolv.conf"
+  fi
+
   assert [ ${#lines[@]} -eq 1 ]
 
   # shellcheck disable=SC2154