I could not find tarball for 2.1 so I updated

also remove useless environment option which has same value as the macro

(+ small cosmetic fixes)

All instances in the wild have now moved their DB
from srv/res6stnet/registry to srv/re6stnet.

See commit a1ed9c30.

Fallback to alternate-url only happens on HTTPError.

SSL certificate of people.redhat.com has bad chain, which results with failed
downloads.

mysql: With universal_newlines, python3 subprocess assumes that communicate() parameter is str() (not bytes()).

But mysql_script_file was opened as a binary files and thus a bytes() was returned:
    File "etc/run/mariadb_update", line 51, in <module>
      sys.exit(slapos.recipe.generic_mysql.mysql.updateMysql(mysql_upgrade_binary='/srv/slapgrid/slappart3/bin/mysql_upgrade', mysql_binary='/srv/slapgrid/slappart3/bin/mysql', mysql_script_file='/srv/slapgrid/slappart3/etc/mariadb_initial_setup.sql'))
    File "parts/slapos.cookbook-repository/slapos/recipe/generic_mysql/mysql.py", line 31, in updateMysql
      result = mysql.communicate(mysql_script)[0]
    File "parts/python3/lib/python3.7/subprocess.py", line 964, in communicate
      stdout, stderr = self._communicate(input, endtime, timeout)
    File "parts/python3/lib/python3.7/subprocess.py", line 1692, in _communicate
      self._save_input(input)
    File "parts/python3/lib/python3.7/subprocess.py", line 1774, in _save_input
      self._input = self._input.encode(self.stdin.encoding,
  AttributeError: 'bytes' object has no attribute 'encode'

See merge request nexedi/slapos!1135

Using macros.cfg to add a new macro.
This macro will works like [macro-virtual-env].
Neverthless, it will use pygolang to create a more "classic" interpreter.

Use the python `six` library to realize the compatibility of `urlparse` in python2 and python3

See merge request nexedi/slapos!1138

See merge request nexedi/slapos!1128

Since da03653908aea9a62f805faf0328f7b2f046abaa slapos.core's slapproxy transmit
more parameters, so adapt tests to account for it.

The https://bz.apache.org/bugzilla/show_bug.cgi?id=65769 seems hitting
various software releases with strace like:

select(0, NULL, NULL, NULL, {tv_sec=1, tv_usec=0}) = 0 (Timeout)
wait4(-1, 0x7ffe9579eb84, WNOHANG|WSTOPPED, NULL) = -1 ECHILD (No child processes)
times({tms_utime=561, tms_stime=669, tms_cutime=558, tms_cstime=99}) = 3280801757

Also adapt the --with-pcre switch in order to find the pcre-config during the
build process.