line_length: Allow mapping values with long unbreakable lines

yamllint/rules/line_length.py

@@ -72,6 +72,7 @@ Use this rule to set a limit to lines length.
             http://localhost/very/very/very/very/very/very/very/very/long/url
 """
 
+import yaml
 
 from yamllint.linter import LintProblem
 
@@ -96,6 +97,11 @@ def check(conf, line):
                 if line.buffer.find(' ', start, line.end) == -1:
                     return
 
+                line_yaml = yaml.safe_load(line.content)
+                if (isinstance(line_yaml, dict) and
+                        ' ' not in line_yaml.popitem()[1]):
+                    return
+
         yield LintProblem(line.line_no, conf['max'] + 1,
                           'line too long (%d > %d characters)' %
                           (line.end - line.start, conf['max']))