Fix IDE commit to use start_ref59023-fix-web-ide-creating-branches-off-new-commits

**Why?**
The branch HEAD could be changed since the
IDE was opened. This leads to user's unintentionally
creating commits that overwrite other changes.

https://gitlab.com/gitlab-org/gitlab-ce/issues/59023

3 files changed, 17 insertions, 3 deletions

diff --git a/app/assets/javascripts/ide/services/index.js b/app/assets/javascripts/ide/services/index.js
index ba33b6826d6..840761f68db 100644
--- a/app/assets/javascripts/ide/services/index.js
+++ b/app/assets/javascripts/ide/services/index.js
@@ -56,7 +56,13 @@ export default {
     return Api.branchSingle(projectId, currentBranchId);
   },
   commit(projectId, payload) {
-    return Api.commitMultiple(projectId, payload);
+    // Currently the `commit` endpoint does not support `start_sha` so we
+    // have to make the request in the FE. This is not ideal and will be
+    // resolved soon. https://gitlab.com/gitlab-org/gitlab-ce/issues/59023
+    const { branch, start_sha: ref } = payload;
+    const branchPromise = ref ? Api.createBranch(projectId, { ref, branch }) : Promise.resolve();
+
+    return branchPromise.then(() => Api.commitMultiple(projectId, payload));
   },
   getFiles(projectUrl, branchId) {
     const url = `${projectUrl}/files/${branchId}`;
diff --git a/app/assets/javascripts/ide/stores/modules/commit/actions.js b/app/assets/javascripts/ide/stores/modules/commit/actions.js
index 51062f092ad..ff1255ce749 100644
--- a/app/assets/javascripts/ide/stores/modules/commit/actions.js
+++ b/app/assets/javascripts/ide/stores/modules/commit/actions.js
@@ -142,6 +142,7 @@ export const commitChanges = ({ commit, state, getters, dispatch, rootState, roo
         getters,
         state,
         rootState,
+        rootGetters,
       });
 
       return service.commit(rootState.currentProjectId, payload);
diff --git a/app/assets/javascripts/ide/stores/utils.js b/app/assets/javascripts/ide/stores/utils.js
index bcc9ca60d9b..4e7a8765abe 100644
--- a/app/assets/javascripts/ide/stores/utils.js
+++ b/app/assets/javascripts/ide/stores/utils.js
@@ -135,7 +135,14 @@ export const getCommitFiles = stagedFiles =>
     });
   }, []);
 
-export const createCommitPayload = ({ branch, getters, newBranch, state, rootState }) => ({
+export const createCommitPayload = ({
+  branch,
+  getters,
+  newBranch,
+  state,
+  rootState,
+  rootGetters,
+}) => ({
   branch,
   commit_message: state.commitMessage || getters.preBuiltCommitMessage,
   actions: getCommitFiles(rootState.stagedFiles).map(f => ({
@@ -146,7 +153,7 @@ export const createCommitPayload = ({ branch, getters, newBranch, state, rootSta
     encoding: f.base64 ? 'base64' : 'text',
     last_commit_id: newBranch || f.deleted || f.prevPath ? undefined : f.lastCommitSha,
   })),
-  start_branch: newBranch ? rootState.currentBranchId : undefined,
+  start_sha: newBranch ? rootGetters.lastCommit.short_id : undefined,
 });
 
 export const createNewMergeRequestUrl = (projectUrl, source, target) =>