Merge branch 'qutebrowser:master' into master

doc/changelog.asciidoc

@@ -45,6 +45,8 @@ Changed
 - The `qute-bitwarden` userscript understands a new
   `--password-prompt-invocation`, which can be used to specify a tool other
   than `rofi` to ask for a password.
+- The `content.headers.custom` setting now accepts empty strings as values,
+  resulting in an empty header being sent.
 
 Added
 ~~~~~

qutebrowser/browser/shared.py

@@ -51,7 +51,9 @@ def custom_headers(url):
 
     conf_headers = config.instance.get('content.headers.custom', url=url)
     for header, value in conf_headers.items():
-        headers[header.encode('ascii')] = value.encode('ascii')
+        encoded_header = header.encode('ascii')
+        encoded_value = b"" if value is None else value.encode('ascii')
+        headers[encoded_header] = encoded_value
 
     accept_language = config.instance.get('content.headers.accept_language',
                                           url=url)

qutebrowser/config/configdata.yml

@@ -616,6 +616,7 @@ content.headers.custom:
     valtype:
       name: String
       encoding: ascii
+      none_ok: true
     none_ok: true
   supports_pattern: true
   desc: Custom headers for qutebrowser HTTP requests.