Add test for file conflicts on upgrade of the same package

This allows to be certain that we don't raise a conflict error while
upgrading the same package

tests/fixtures/nofileconflicts_upgrade/noconflict/build.yaml

@@ -0,0 +1,6 @@
+image: "alpine"
+prelude:
+  - mkdir /foo
+steps:
+  - echo conflict > /foo/test1
+package_dir: /foo

tests/fixtures/nofileconflicts_upgrade/noconflict/collection.yaml

@@ -0,0 +1,7 @@
+packages:
+- category: "test1"
+  name: "noconflict"
+  version: "1.0"
+- category: "test1"
+  name: "noconflict"
+  version: "1.1"

tests/integration/32_nofileconflicts_upgrade.sh

@@ -0,0 +1,78 @@
+#!/bin/bash
+
+export LUET_NOLOCK=true
+
+oneTimeSetUp() {
+export tmpdir="$(mktemp -d)"
+}
+
+oneTimeTearDown() {
+    rm -rf "$tmpdir"
+}
+
+testBuild() {
+    mkdir $tmpdir/testbuild
+    luet build --tree "$ROOT_DIR/tests/fixtures/nofileconflicts_upgrade" --destination $tmpdir/testbuild --compression gzip --all
+    buildst=$?
+    assertEquals 'builds successfully' "$buildst" "0"
+    assertTrue 'create packages' "[ -e '$tmpdir/testbuild/noconflict-test1-1.0.package.tar.gz' ]"
+    assertTrue 'create packages' "[ -e '$tmpdir/testbuild/noconflict-test1-1.1.package.tar.gz' ]"
+}
+
+testRepo() {
+    assertTrue 'no repository' "[ ! -e '$tmpdir/testbuild/repository.yaml' ]"
+    luet create-repo --tree "$ROOT_DIR/tests/fixtures/nofileconflicts_upgrade" \
+    --output $tmpdir/testbuild \
+    --packages $tmpdir/testbuild \
+    --name "test" \
+    --descr "Test Repo" \
+    --urls $tmpdir/testrootfs \
+    --type disk > /dev/null
+
+    createst=$?
+    assertEquals 'create repo successfully' "$createst" "0"
+    assertTrue 'create repository' "[ -e '$tmpdir/testbuild/repository.yaml' ]"
+}
+
+testConfig() {
+    mkdir $tmpdir/testrootfs
+    cat <<EOF > $tmpdir/luet.yaml
+general:
+  debug: true
+system:
+  rootfs: $tmpdir/testrootfs
+  database_path: "/"
+  database_engine: "boltdb"
+config_from_host: true
+repositories:
+   - name: "main"
+     type: "disk"
+     enable: true
+     urls:
+       - "$tmpdir/testbuild"
+EOF
+    luet config --config $tmpdir/luet.yaml
+    res=$?
+    assertEquals 'config test successfully' "$res" "0"
+}
+
+testInstall() {
+    luet install -y --config $tmpdir/luet.yaml test1/noconflict@1.0
+    installst=$?
+    #assertTrue 'package installed' "[ -e '$tmpdir/testrootfs/c' ]"
+}
+
+testUpgrade() {
+    out=$(luet upgrade -y --config $tmpdir/luet.yaml)
+    installst=$?
+    assertEquals 'install test succeeded' "$installst" "0"
+    assertNotContains 'does find conflicts' "$out" "Error: file conflict found: file conflict between packages to be installed"
+
+    installed=$(luet --config $tmpdir/luet.yaml search --installed)
+    assertContains 'does upgrade' "$installed" "test1/noconflict-1.1"
+
+}
+
+# Load shUnit2.
+. "$ROOT_DIR/tests/integration/shunit2"/shunit2
+