maint: improve bootstrap resilience

Make the bootstrap initialization more resilient to errors.

Relates-to: keymanapp/shared-sites#90
Test-bot: skip

Author: mcdurdin

.gitignore

@@ -2,5 +2,6 @@
 # Shared files are bootstrapped:
 resources/bootstrap.inc.sh
 resources/.bootstrap-version
+resources/.bootstrap-registry
 _common/
 

build.sh

@@ -3,7 +3,11 @@
 readonly THIS_SCRIPT="$(readlink -f "${BASH_SOURCE[0]}")"
 readonly BOOTSTRAP="$(dirname "$THIS_SCRIPT")/resources/bootstrap.inc.sh"
 readonly BOOTSTRAP_VERSION=v1.0.10
-[ -f "$BOOTSTRAP" ] && source "$BOOTSTRAP" || source <(curl -fs https://raw.githubusercontent.com/keymanapp/shared-sites/$BOOTSTRAP_VERSION/bootstrap.inc.sh)
+if ! [ -f "$BOOTSTRAP" ] || ! source "$BOOTSTRAP"; then
+  curl -H "Cache-Control: no-cache" --fail --silent --show-error -w "curl: Finished attempt to download %{url}" "https://raw.githubusercontent.com/keymanapp/shared-sites/$BOOTSTRAP_VERSION/bootstrap.inc.sh" -o "$BOOTSTRAP.tmp" || exit 1
+  source "$BOOTSTRAP.tmp"
+  rm -f "$BOOTSTRAP.tmp"
+fi
 ## END STANDARD SITE BUILD SCRIPT INCLUDE
 
 readonly PROXY_CONTAINER_NAME=local-proxy-website