update: repair tap on missing remote ref

- automatically run `brew tap --repair` when we detect it's needed
- don't pass list of taps to repair taps to update-report; no longer
  since update repairs them

Library/Homebrew/cmd/update-report.rb

@@ -259,19 +259,6 @@ def output_update_report
         link_completions_manpages_and_docs
         Tap.installed.each(&:link_completions_and_manpages)
 
-        failed_fetch_dirs = ENV["HOMEBREW_MISSING_REMOTE_REF_DIRS"]&.split("\n")
-        if failed_fetch_dirs.present?
-          failed_fetch_taps = failed_fetch_dirs.map { |dir| Tap.from_path(dir) }
-
-          ofail <<~EOS
-            Some taps failed to update!
-            The following taps can not read their remote branches:
-              #{failed_fetch_taps.join("\n  ")}
-            This is happening because the remote branch was renamed or deleted.
-            Reset taps to point to the correct remote branches by running `brew tap --repair`
-          EOS
-        end
-
         return if new_tag.blank? || new_tag == old_tag || args.quiet?
 
         puts

Library/Homebrew/cmd/update.sh

@@ -328,6 +328,7 @@ EOS
 }
 
 fetch_tags() {
+  local retry=$1
   local fail_silently="${HOMEBREW_UPDATE_AUTO}"
 
   if [[ -n "${HOMEBREW_VERBOSE}" ]]
@@ -347,6 +348,7 @@ fetch_tags() {
     then
       # Looks like upstream HEAD branch has been renamed.
       echo "${DIR}" >>"${missing_remote_ref_dirs_file}"
+      [[ -z "${retry}" ]] && fail_silently=1
     fi
 
     if [[ -z "${fail_silently}" ]]
@@ -764,9 +766,19 @@ EOS
 
   if [[ -f "${missing_remote_ref_dirs_file}" ]]
   then
-    HOMEBREW_MISSING_REMOTE_REF_DIRS="$(cat "${missing_remote_ref_dirs_file}")"
+    while IFS='' read -r DIR
+    do
+      brew tap --repair ${HOMEBREW_VERBOSE+--verbose} "${DIR#"${HOMEBREW_LIBRARY}"/Taps/}"
+
+      cd "${DIR}"
+      TAP_VAR="$(repository_var_suffix "${DIR}")"
+      UPSTREAM_BRANCH_DIR="$(upstream_branch)"
+      declare UPSTREAM_BRANCH"${TAP_VAR}"="${UPSTREAM_BRANCH_DIR}"
+
+      fetch_tags retry
+    done <"${missing_remote_ref_dirs_file}"
+
     rm -f "${missing_remote_ref_dirs_file}"
-    export HOMEBREW_MISSING_REMOTE_REF_DIRS
   fi
 
   for DIR in "${HOMEBREW_REPOSITORY}" "${HOMEBREW_LIBRARY}"/Taps/*/*
@@ -914,7 +926,6 @@ EOS
   # shellcheck disable=SC2031
   if [[ -n "${HOMEBREW_UPDATED}" ]] ||
      [[ -n "${HOMEBREW_UPDATE_FAILED}" ]] ||
-     [[ -n "${HOMEBREW_MISSING_REMOTE_REF_DIRS}" ]] ||
      [[ -n "${HOMEBREW_UPDATE_FORCE}" ]] ||
      [[ -n "${HOMEBREW_MIGRATE_LINUXBREW_FORMULAE}" ]] ||
      [[ -d "${HOMEBREW_LIBRARY}/LinkedKegs" ]] ||