Retry failing zeroconf scripts for Pharo

Fixes #617

helpers.sh

@@ -639,6 +639,24 @@ deploy() {
   fold_end deploy
 }
 
+retry() {
+  local retries=$1
+  local command=$2
+  local status=0
+
+  $command || status=$?
+
+  if [[ $status -ne 0 ]]; then
+    if [[ $retries -gt 0 ]]; then
+      echo "Retrying in one second..."
+      sleep 1
+      retry $(($retries - 1)) "$command"
+    else
+      print_error_and_exit "The command '${command}' failed too often (last exit code: ${status})."
+    fi
+  fi
+}
+
 
 ################################################################################
 # Travis-related helper functions (based on https://git.io/vzcTj).

pharo/run.sh

@@ -247,7 +247,7 @@ pharo::prepare_vm() {
     pushd "${config_vm_dir}" > /dev/null
     fold_start download_vm "Downloading ${smalltalk_name} vm..."
       download_file "${pharo_vm_url}" "${pharo_zeroconf}"
-      bash "${pharo_zeroconf}"
+      retry 3 "bash ${pharo_zeroconf}"
     fold_end download_vm
     popd > /dev/null
   fi
@@ -283,7 +283,7 @@ pharo::prepare_image() {
     pushd "${target}" > /dev/null
     fold_start download_image "Downloading ${smalltalk_name} image..."
       download_file "${pharo_image_url}" "${pharo_zeroconf}"
-      bash "${pharo_zeroconf}"
+      retry 3 "bash ${pharo_zeroconf}"
     fold_end download_image
     popd > /dev/null
   fi