wscript checking versions fails with non-numeric characters

The current version of asciidoctor in ubuntu focal is 9.0.0rc1

The current version in debian/testing is also 9.0.0rc1

This breaks the wscript around line 163

sanjeev@T450s-disco:~/SRC/ntpsec$ ./waf configure --enable-doc
Setting top to                           : /home/sanjeev/SRC/ntpsec 
Setting out to                           : /home/sanjeev/SRC/ntpsec/build 
--- Configuring host --- 
Checking for 'gcc' (C compiler)          : /usr/bin/gcc 
Checking compiler version                : 9.2.1 
Checking for program 'm4'                : /usr/bin/m4 
Checking for program 'bison'             : /usr/bin/bison 
Checking for program 'awk'               : /usr/bin/awk 
Checking for program 'sh'                : /usr/bin/sh 
Checking for program 'asciidoc'          : /usr/bin/asciidoc 
Traceback (most recent call last):
  File "/home/sanjeev/SRC/ntpsec/.waf-2.0.18-2196dde88c146cbf99e9e4d00621cfc8/waflib/Scripting.py", line 119, in waf_entry_point
    run_commands()
  File "/home/sanjeev/SRC/ntpsec/.waf-2.0.18-2196dde88c146cbf99e9e4d00621cfc8/waflib/Scripting.py", line 182, in run_commands
    ctx=run_command(cmd_name)
  File "/home/sanjeev/SRC/ntpsec/.waf-2.0.18-2196dde88c146cbf99e9e4d00621cfc8/waflib/Scripting.py", line 173, in run_command
    ctx.execute()
  File "/home/sanjeev/SRC/ntpsec/.waf-2.0.18-2196dde88c146cbf99e9e4d00621cfc8/waflib/Configure.py", line 85, in execute
    super(ConfigurationContext,self).execute()
  File "/home/sanjeev/SRC/ntpsec/.waf-2.0.18-2196dde88c146cbf99e9e4d00621cfc8/waflib/Context.py", line 85, in execute
    self.recurse([os.path.dirname(g_module.root_path)])
  File "/home/sanjeev/SRC/ntpsec/.waf-2.0.18-2196dde88c146cbf99e9e4d00621cfc8/waflib/Context.py", line 126, in recurse
    user_function(self)
  File "/home/sanjeev/SRC/ntpsec/wscript", line 163, in configure
    asciidocver_tuple = (int(lines[0]), int(lines[1]), int(lines[2]))
ValueError: invalid literal for int() with base 10: '0rc1'
sanjeev@T450s-disco:~/SRC/ntpsec$ asciidoc --version
asciidoc 9.0.0rc1