Update gem behind proxy

I tried to update gem behind a proxy and got the following error message:

Though the http_proxy and https_proxy (also in upper case) was set it didn’t work.¬† Trying to set the proxy directly in the command did the trick:

opensuse: nokogiri gem installation fails

Extracting libxml2-2.9.2.tar.gz into tmp/x86_64-suse-linux-gnu/ports/libxml2/2.9.2… OK
Running patch with /usr/lib64/ruby/gems/2.1.0/gems/nokogiri-…
Running ‘patch’ for libxml2 2.9.2… ERROR, review ‘/usr/lib64/ruby/gems/2.1.0/gems/nokogiri-’ to see what happened.
*** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of necessary
libraries and/or headers. Check the mkmf.log file for more details. You may
need configuration options.

The mentioned log tells us that patch executable is not installed. Fixed by: