Change target branch for pull request (#6488)

* Adds functionality to change target branch of created pull requests

Signed-off-by: Mario Lubenka <mario.lubenka@googlemail.com>

* Use const instead of var in JavaScript additions

Signed-off-by: Mario Lubenka <mario.lubenka@googlemail.com>

* Check if branches are equal and if PR already exists before changing target branch

Signed-off-by: Mario Lubenka <mario.lubenka@googlemail.com>

* Make sure to check all commits

Signed-off-by: Mario Lubenka <mario.lubenka@googlemail.com>

* Print error messages for user as error flash message

Signed-off-by: Mario Lubenka <mario.lubenka@googlemail.com>

* Disallow changing target branch of closed or merged pull requests

Signed-off-by: Mario Lubenka <mario.lubenka@googlemail.com>

* Resolve conflicts after merge of upstream/master

Signed-off-by: Mario Lubenka <mario.lubenka@googlemail.com>

* Change order of branch select fields

Signed-off-by: Mario Lubenka <mario.lubenka@googlemail.com>

* Removes duplicate check

Signed-off-by: Mario Lubenka <mario.lubenka@googlemail.com>

* Use ctx.Tr for translations

Signed-off-by: Mario Lubenka <mario.lubenka@googlemail.com>

* Recompile JS

Signed-off-by: Mario Lubenka <mario.lubenka@googlemail.com>

* Use correct translation namespace

Signed-off-by: Mario Lubenka <mario.lubenka@googlemail.com>

* Remove redundant if condition

Signed-off-by: Mario Lubenka <mario.lubenka@googlemail.com>

* Moves most change branch logic into pull service

Signed-off-by: Mario Lubenka <mario.lubenka@googlemail.com>

* Completes comment

Signed-off-by: Mario Lubenka <mario.lubenka@googlemail.com>

* Add Ref to ChangesPayload for logging changed target branches
instead of creating a new struct

Signed-off-by: Mario Lubenka <mario.lubenka@googlemail.com>

* Revert changes to go.mod

Signed-off-by: Mario Lubenka <mario.lubenka@googlemail.com>

* Directly use createComment method

Signed-off-by: Mario Lubenka <mario.lubenka@googlemail.com>

* Return 404 if pull request is not found. Move written check up

Signed-off-by: Mario Lubenka <mario.lubenka@googlemail.com>

* Remove variable declaration

Signed-off-by: Mario Lubenka <mario.lubenka@googlemail.com>

* Return client errors on change pull request target errors

Signed-off-by: Mario Lubenka <mario.lubenka@googlemail.com>

* Return error in commit.HasPreviousCommit

Signed-off-by: Mario Lubenka <mario.lubenka@googlemail.com>

* Adds blank line

Signed-off-by: Mario Lubenka <mario.lubenka@googlemail.com>

* Test patch before persisting new target branch

Signed-off-by: Mario Lubenka <mario.lubenka@googlemail.com>

* Update patch before testing (not working)

Signed-off-by: Mario Lubenka <mario.lubenka@googlemail.com>

* Removes patch calls when changeing pull request target

Signed-off-by: Mario Lubenka <mario.lubenka@googlemail.com>

* Removes unneeded check for base name

Signed-off-by: Mario Lubenka <mario.lubenka@googlemail.com>

* Moves ChangeTargetBranch completely to pull service. Update patch status.

Signed-off-by: Mario Lubenka <mario.lubenka@googlemail.com>

* Set webhook mode after errors were validated

Signed-off-by: Mario Lubenka <mario.lubenka@googlemail.com>

* Update PR in one transaction

Signed-off-by: Mario Lubenka <mario.lubenka@googlemail.com>

* Move logic for check if head is equal with branch to pull model

Signed-off-by: Mario Lubenka <mario.lubenka@googlemail.com>

* Adds missing comment and simplify return

Signed-off-by: Mario Lubenka <mario.lubenka@googlemail.com>

* Adjust CreateComment method call

Signed-off-by: Mario Lubenka <mario.lubenka@googlemail.com>

options/locale/locale_en-US.ini

@@ -1033,8 +1033,9 @@ pulls.no_results = No results found.
 pulls.nothing_to_compare = These branches are equal. There is no need to create a pull request.
 pulls.has_pull_request = `A pull request between these branches already exists: <a href="%[1]s/pulls/%[3]d">%[2]s#%[3]d</a>`
 pulls.create = Create Pull Request
-pulls.title_desc = wants to merge %[1]d commits from <code>%[2]s</code> into <code>%[3]s</code>
+pulls.title_desc = wants to merge %[1]d commits from <code>%[2]s</code> into <code id="branch_target">%[3]s</code>
 pulls.merged_title_desc = merged %[1]d commits from <code>%[2]s</code> into <code>%[3]s</code> %[4]s
+pulls.change_target_branch_at = `changed target branch from <b>%s</b> to <b>%s</b> %s`
 pulls.tab_conversation = Conversation
 pulls.tab_commits = Commits
 pulls.tab_files = Files Changed
@@ -1042,6 +1043,7 @@ pulls.reopen_to_merge = Please reopen this pull request to perform a merge.
 pulls.cant_reopen_deleted_branch = This pull request cannot be reopened because the branch was deleted.
 pulls.merged = Merged
 pulls.merged_as = The pull request has been merged as <a rel="nofollow" class="ui sha" href="%[1]s"><code>%[2]s</code></a>.
+pulls.is_closed = The pull request has been closed.
 pulls.has_merged = The pull request has been merged.
 pulls.title_wip_desc = `<a href="#">Start the title with <strong>%s</strong></a> to prevent the pull request from being merged accidentally.`
 pulls.cannot_merge_work_in_progress = This pull request is marked as a work in progress. Remove the <strong>%s</strong> prefix from the title when it's ready