build_library/catalyst.sh: Fix and extend snapshot handling

- Fix the snapshot name, it is not "portage-${VERSION}", but rather
  "gentoo-${VERSION}".

- After building the snapshot, remove all the similar files from the
  snapshots directory - Catalyst gets easily confused by them and
  bails out.

- Extend the `build_snapshot` function to optionally accept the config
  path and the snapshot name, so SDK's stage1 code can use this
  function instead of duplicating parts of it.

bootstrap_sdk

@@ -201,11 +201,7 @@ build_stage1() {
     sed -i "s:^portdir.*:portdir=\"$stage1_repos/gentoo\":" \
          "$TEMPDIR/catalyst-stage1.conf"
     # take the "portage directory" (portage-stable copy) snapshot
-    catalyst \
-        "${DEBUG[@]}" \
-        --verbose \
-        --config "$TEMPDIR/catalyst-stage1.conf" \
-        --snapshot "$FLAGS_version-stage1"
+    build_snapshot "${TEMPDIR}/catalyst-stage1.conf" "${FLAGS_version}-stage1"
 
     # Update the stage 1 spec to use the "known-good" portage-stable snapshot
     #  and coreos-overlay copy repository versions from above.

build_library/catalyst.sh

@@ -272,7 +272,7 @@ build_stage() {
         --config "$TEMPDIR/catalyst.conf" \
         --file "$TEMPDIR/${stage}.spec" \
         --cli "source_subpath=$srcpath"
-    # Catalyst doesn't clean up after itself...
+    # Catalyst does not clean up after itself...
     rm -rf "$TEMPDIR/$stage-${ARCH}-${FLAGS_version}"
     ln -sf "$stage-${ARCH}-${FLAGS_version}.tar.bz2" \
         "$BUILDS/$stage-${ARCH}-latest.tar.bz2"
@@ -280,8 +280,13 @@ build_stage() {
 }
 
 build_snapshot() {
-    local snapshot="portage-${FLAGS_version}.tar.bz2"
-    local snapshot_path="$CATALYST_ROOT/snapshots/${snapshot}"
+    local catalyst_conf snapshot snapshots_dir snapshot_base snapshot_path
+
+    catalyst_conf=${1:-"${TEMPDIR}/catalyst.conf"}
+    snapshot=${2:-"${FLAGS_version}"}
+    snapshots_dir="${CATALYST_ROOT}/snapshots"
+    snapshot_base="${snapshots_dir}/gentoo-${snapshot}"
+    snapshot_path="${snapshot_base}.tar.bz2"
     if [[ -f "${snapshot_path}" && $FLAGS_rebuild == $FLAGS_FALSE ]]
     then
         info "Skipping snapshot, ${snapshot_path} exists"
@@ -290,8 +295,31 @@ build_snapshot() {
         catalyst \
             "${DEBUG[@]}" \
             --verbose \
-            --config "$TEMPDIR/catalyst.conf" \
-            --snapshot "$FLAGS_version"
+            --config "${catalyst_conf}" \
+            --snapshot "${snapshot}"
+    fi
+    local f
+    local to_remove=()
+    # This will expand to at least our just built snapshot tarball, so
+    # no nullglob is needed here.
+    for f in "${snapshot_base}".*; do
+        case "${f}" in
+            "${snapshot_path}")
+                # Our snapshot, keep it as is.
+                :
+                ;;
+            *.CONTENTS|*.CONTENTS.gz|*.DIGESTS)
+                # These can stay, catalyst is not bothered by those.
+                :
+                ;;
+            *)
+                to_remove+=("${f}")
+                ;;
+        esac
+    done
+    if [[ ${#to_remove[@]} -gt 0 ]]; then
+        info "$(printf '%s\n' 'Found spurious files in snapshots directory that may confuse Catalyst, removing them:' "${to_remove[@]}")"
+        rm -rf "${to_remove[@]}"
     fi
 }
 
@@ -336,5 +364,5 @@ catalyst_build() {
     fi
 
     # Cleanup snapshots, we don't use them
-    rm -rf "$CATALYST_ROOT/snapshots/portage-${FLAGS_version}.tar.bz2"*
+    rm -rf "$CATALYST_ROOT/snapshots/gentoo-${FLAGS_version}.tar.bz2"*
 }