Check for empty string when configuring proxies

On some Linux system like debian, the `HTTP_PROXY` are set to an empty
string and was causing the plugin manager to raise an exception. We now
strip the string and check if it is empty before trying to configure the
proxies.

Fixes: #7045

Fixes #7065

lib/pluginmanager/proxy_support.rb

@@ -56,14 +56,16 @@ end
 
 def configure_proxy
   proxies = []
-  if proxy = (ENV["http_proxy"] || ENV["HTTP_PROXY"])
+  proxy = (ENV["http_proxy"] || ENV["HTTP_PROXY"])
+  if !proxy.nil? && !proxy.strip.empty?
     proxy_settings = extract_proxy_values_from_uri(proxy)
     proxy_settings[:protocol] = "http"
     apply_env_proxy_settings(proxy_settings)
     proxies << proxy_settings
   end
 
-  if proxy = (ENV["https_proxy"] || ENV["HTTPS_PROXY"])
+  proxy = (ENV["https_proxy"] || ENV["HTTPS_PROXY"])
+  if !proxy.nil? && !proxy.strip.empty?
     proxy_settings = extract_proxy_values_from_uri(proxy)
     proxy_settings[:protocol] = "https"
     apply_env_proxy_settings(proxy_settings)

spec/unit/plugin_manager/proxy_support_spec.rb

@@ -112,4 +112,21 @@ describe "Proxy support" do
       }
     end
   end
+
+  context "when proxies are set with an empty string" do
+    let(:environments) {
+      {
+        "http_proxy" => "",
+        "https_proxy" => ""
+      }
+    }
+
+    before do
+      environments.each { |key, value| ENV[key] = value }
+    end
+
+    it "doesn't raise an exception" do
+      expect { configure_proxy }.not_to raise_exception
+    end
+  end
 end