macOS BigSur dir_chdir error when installing to ruby 2.7.1

[AstroCX1]

Any one else see something similar? works in 2.5.3. Using rvm to install 2.7.1. All other gems seem to be just fine.

current directory: /Users/ab/.rvm/gems/ruby-2.7.1/gems/digest-crc-0.6.3/ext/digest
["/Users/ab/.rvm/rubies/ruby-2.7.1/bin/ruby", "-I/Users/ab/.rvm/rubies/ruby-2.7.1/lib/ruby/2.7.0/rubygems", "-rrubygems", "/Users/ab/.rvm/gems/ruby-2.7.1/gems/rake-13.0.3/exe/rake", "RUBYARCHDIR=/Users/ab/.rvm/gems/ruby-2.7.1/extensions/x86_64-darwin-20/2.7.0/digest-crc-0.6.3", "RUBYLIBDIR=/Users/ab/.rvm/gems/ruby-2.7.1/extensions/x86_64-darwin-20/2.7.0/digest-crc-0.6.3"]
/Users/ab/.rvm/rubies/ruby-2.7.1/bin/ruby -S extconf.rb
checking for stdint.h... yes
checking for stddef.h... yes
creating extconf.h
creating Makefile
rake aborted!
Errno::EINTR: Interrupted system call @ dir_chdir - /Users/ab/.rvm/gems/ruby-2.7.1/gems/digest-crc-0.6.3/ext/digest
/Users/ab/.rvm/gems/ruby-2.7.1/gems/digest-crc-0.6.3/ext/digest/Rakefile:23:in `chdir'
/Users/ab/.rvm/gems/ruby-2.7.1/gems/digest-crc-0.6.3/ext/digest/Rakefile:23:in `block (2 levels) in <top (required)>'
/Users/ab/.rvm/gems/ruby-2.7.1/gems/rake-13.0.3/exe/rake:27:in `<main>'
Tasks: TOP => default => crc16_genibus/crc16_genibus_ext.bundle => crc16_genibus/Makefile
(See full trace by running task with --trace)
ERROR:  Error installing digest-crc:
	ERROR: Failed to build gem native extension.

    current directory: /Users/ab/.rvm/gems/ruby-2.7.1/gems/digest-crc-0.6.3/ext/digest
/Users/ab/.rvm/rubies/ruby-2.7.1/bin/ruby -I/Users/ab/.rvm/rubies/ruby-2.7.1/lib/ruby/2.7.0/rubygems -rrubygems /Users/ab/.rvm/gems/ruby-2.7.1/gems/rake-13.0.3/exe/rake RUBYARCHDIR\=/Users/ab/.rvm/gems/ruby-2.7.1/extensions/x86_64-darwin-20/2.7.0/digest-crc-0.6.3 RUBYLIBDIR\=/Users/ab/.rvm/gems/ruby-2.7.1/extensions/x86_64-darwin-20/2.7.0/digest-crc-0.6.3
Building has failed. See above output for more information on the failure.
rake failed, exit code 1

Gem files will remain installed in /Users/ab/.rvm/gems/ruby-2.7.1/gems/digest-crc-0.6.3 for inspection.
Results logged to /Users/ab/.rvm/gems/ruby-2.7.1/extensions/x86_64-darwin-20/2.7.0/digest-crc-0.6.3/gem_make.out

[AstroCX1]

Adding a sleep in Rakefile seems to help build for spec at least. No clue why.

  file "#{crc}/#{crc_ext_lib}" => "#{crc}/Makefile" do
    Dir.chdir(crc) do
      begin
        sh 'make', 'clean'
        sh 'make'
      rescue
        fail_gracefully "Unable to build C extensions"
      end
      sleep(1) # this helps? No idea why
    end
  end