Disable merging a WIP Pull request (#4529)

* prevent pull request to be merged when PR is a WIP

* add tests

* add helper to prepend WIP: in PR title

* move default wip prefixes into settings

* use configurable WIP prefixes in javascript and default to first one in templates

* add documentation

* add unit test on pull model

Signed-off-by: Julien Tant <julien@craftyx.fr>

docs/content/doc/advanced/config-cheat-sheet.en-us.md

@@ -62,6 +62,10 @@ Values containing `#` or `;` must be quoted using `` ` `` or `"""`.
    HTTP protocol.
 - `USE_COMPAT_SSH_URI`: **false**: Force ssh:// clone url instead of scp-style uri when
    default SSH port is used.
+   
+### Repository - Pull Request (`repository.pull-request`)
+- `WORK_IN_PROGRESS_PREFIXES`: **WIP:,\[WIP\]**: List of prefixes used in Pull Request
+ title to mark them as Work In Progress
 
 ## UI (`ui`)
 

docs/content/doc/usage/pull-request.en-us.md

@@ -0,0 +1,31 @@
+---
+date: "2018-06-01T19:00:00+02:00"
+title: "Usage: Pull Request"
+slug: "pull-request"
+weight: 13
+toc: true
+draft: false
+menu:
+  sidebar:
+    parent: "usage"
+    name: "Pull Request"
+    weight: 13
+    identifier: "pull-request"
+---
+
+# Pull Request
+
+## "Work In Progress" pull requests
+
+Marking a pull request as being a work in progress will prevent that pull request from being accidentally merged. To mark a pull request as being a work in progress, you must prefix its title by `WIP:` or `[WIP]` (case insensitive). Those values are configurable in your `app.ini` file :
+
+```
+[repository.pull-request]
+WORK_IN_PROGRESS_PREFIXES=WIP:,[WIP]
+```
+
+The first value of the list will be used in helpers.
+
+## Pull Request Templates
+
+You can find more information about pull request templates in the dedicated page : [Issue and Pull Request templates](../issue-pull-request-templates)