pkgsrc/lang/npm build failure: IPv6 failed connection

Attempting to build pkgsrc/lang/npm on an IPv4 connected netbsd-9/amd64 box is failing for me with:

+ node . i --ignore-scripts --no-audit --no-fund

npm ERR! code EHOSTUNREACH
npm ERR! syscall connect
npm ERR! errno EHOSTUNREACH

npm ERR! request to https://registry.npmjs.org/tap/-/tap-16.0.1.tgz failed, reason: connect EHOSTUNREACH 2606:4700::6810:1823:443 - Local (:::62316)

The file is fetchable via IPv4:

% ftp https://registry.npmjs.org/tap/-/tap-16.0.1.tgz
Trying [2606:4700::6810:1923]:443 ...
ftp: Can't connect to `2606:4700::6810:1923:443': No route to host
Trying [2606:4700::6810:1b23]:443 ...
ftp: Can't connect to `2606:4700::6810:1b23:443': No route to host
Trying [2606:4700::6810:1123]:443 ...
ftp: Can't connect to `2606:4700::6810:1123:443': No route to host
Trying [2606:4700::6810:1523]:443 ...
ftp: Can't connect to `2606:4700::6810:1523:443': No route to host
Trying [2606:4700::6810:1623]:443 ...
ftp: Can't connect to `2606:4700::6810:1623:443': No route to host
Trying [2606:4700::6810:1723]:443 ...
ftp: Can't connect to `2606:4700::6810:1723:443': No route to host
Trying [2606:4700::6810:1223]:443 ...
ftp: Can't connect to `2606:4700::6810:1223:443': No route to host
Trying [2606:4700::6810:1023]:443 ...
ftp: Can't connect to `2606:4700::6810:1023:443': No route to host
Trying [2606:4700::6810:1323]:443 ...
ftp: Can't connect to `2606:4700::6810:1323:443': No route to host
Trying [2606:4700::6810:1423]:443 ...
ftp: Can't connect to `2606:4700::6810:1423:443': No route to host
Trying [2606:4700::6810:1a23]:443 ...
ftp: Can't connect to `2606:4700::6810:1a23:443': No route to host
Trying [2606:4700::6810:1823]:443 ...
ftp: Can't connect to `2606:4700::6810:1823:443': No route to host
Trying 104.16.20.35:443 ...
Requesting https://registry.npmjs.org/tap/-/tap-16.0.1.tgz
100% |***********************************| 6313 KiB 6.60 MiB/s 00:00 ETA
6465462 bytes retrieved in 00:00 (6.60 MiB/s)