problem with (ubuntu/cosmic)mawk /^[[:space:]]*</

#lsb_release -rd

Description: Ubuntu 18.10
Release: 18.10

## package version
#apt-cache policy mawk

mawk:
  Installed: 1.3.3-17ubuntu3
  Candidate: 1.3.3-17ubuntu3
  Version table:
 *** 1.3.3-17ubuntu3 500
        500 http://archive.ubuntu.com/ubuntu cosmic/main amd64 Packages
        100 /var/lib/dpkg/status
###

more background @
https://github.com/whiteinge/ok.sh/issues/66# problem with (ubuntu/cosmic)mawk /^[[:space:]]*</

works as expected with literal ' ' white space
-----
printf %s '<https://api.github.com/repositories/3386088/issues?page=2>; rel="next", <https://api.github.com/repositories/3386088/issues?page=33>; rel="last"' | awk '
                BEGIN { RS=", "; FS="; "; OFS=": " }
                {
                    sub(/^rel="/, "", $2); sub(/"$/, "", $2)
                    sub(/^ *</, "", $1); sub(/>$/, "", $1)
                    print "Link_" $2, $1
                }'
Link_next: https://api.github.com/repositories/3386088/issues?page=2
Link_last: https://api.github.com/repositories/3386088/issues?page=33
-----

fails using [[:space:]]
eg
-----
printf %s '<https://api.github.com/repositories/3386088/issues?page=2>; rel="next", <https://api.github.com/repositories/3386088/issues?page=33>; rel="last"' | awk '
                BEGIN { RS=", "; FS="; "; OFS=": " }
                {
                    sub(/^rel="/, "", $2); sub(/"$/, "", $2)
                    sub(/^[[:space:]]*</, "", $1); sub(/>$/, "", $1)
                    print "Link_" $2, $1
                }'
Link_next: <https://api.github.com/repositories/3386088/issues?page=2
Link_last: <https://api.github.com/repositories/3386088/issues?page=33
-----

eg : https://github.com/dubiouscript/ok.sh/commit/1a6109704653279c21d0b50c34152f674228e1cf

perhaps also relevant
https://bugs.launchpad.net/debian/+source/mawk/+bug/69724
&
https://bugs.launchpad.net/ubuntu/+source/mawk/+bug/1332114#Please update mawk to latest upstream release

0.O