gitlint: ignore titles prefixed with Revert

The revert commit title is usually prefixed with "Revert" which causes
the title to become longer than the allowed limit. Allow such commits to
keep revert commits consistent with the original commit message.

Signed-off-by: Anas Nashif <anas.nashif@intel.com>

.gitlint

@@ -1,6 +1,6 @@
 # All these sections are optional, edit this file as you like.
 [general]
-ignore=title-trailing-punctuation, T3
+ignore=title-trailing-punctuation, T3, title-max-length, T1
 # verbosity should be a value between 1 and 3, the commandline -v flags take precedence over this
 verbosity = 3
 # By default gitlint will ignore merge commits. Set to 'false' to disable.
@@ -12,13 +12,12 @@ debug = false
 # See http://jorisroovers.github.io/gitlint/user_defined_rules for details
 extra-path=scripts/gitlint
 
+[title-max-length-no-revert]
+line-length=72
 
 [body-max-line-count]
 max-line-count=200
 
-[title-max-length]
-line-length=72
-
 [title-starts-with-subsystem]
 regex = ^(([^:]+):)(\s([^:]+):)*\s(.+)$
 

scripts/gitlint/zephyr_commit_rules.py

@@ -55,6 +55,17 @@ class SignedOffBy(CommitRule):
                     return
         return [RuleViolation(self.id, "Body does not contain a 'Signed-Off-By' line", line_nr=1)]
 
+class TitleMaxLengthRevert(LineRule):
+    name = "title-max-length-no-revert"
+    id = "UC5"
+    target = CommitMessageTitle
+    options_spec = [IntOption('line-length', 72, "Max line length")]
+    violation_message = "Title exceeds max length ({0}>{1})"
+
+    def validate(self, line, _commit):
+        max_length = self.options['line-length'].value
+        if len(line) > max_length and not line.startswith("Revert"):
+            return [RuleViolation(self.id, self.violation_message.format(len(line), max_length), line)]
 
 class TitleStartsWithSubsystem(LineRule):
     name = "title-starts-with-subsystem"