update: change repo remotes to HTTPS if possible

Older systems will install Homebrew via git://, but can switch to https:// if a newer curl is installed.

Library/Homebrew/cmd/update.sh

@@ -428,6 +428,15 @@ EOS
 
   safe_cd "$HOMEBREW_REPOSITORY"
 
+  # if an older system had a newer curl installed, change each repo's remote URL from GIT to HTTPS
+  if [[ -n "$HOMEBREW_SYSTEM_CURL_TOO_OLD" &&
+        -x "$HOMEBREW_PREFIX/opt/curl/bin/curl" && 
+        "$(git config remote.origin.url)" =~ ^git:// ]]
+  then
+    git config remote.origin.url "$BREW_OFFICIAL_REMOTE"
+    git config -f "$HOMEBREW_LIBRARY/Taps/homebrew/homebrew-core/.git/config" remote.origin.url "$CORE_OFFICIAL_REMOTE"
+  fi
+
   # kill all of subprocess on interrupt
   trap '{ /usr/bin/pkill -P $$; wait; exit 130; }' SIGINT