resource/gitlab_branch_protection: fix issue claiming that no valid access level can be found. Closes #890

I don't really understand yet what happens here. However, that behavior
changed from v3.9.1 to v3.10.0. Thus, I'm simply reverting it back.

We've had a brief exchange about this already when the "broken" code was
merged here: #881 (comment)

Obviously, we made the wrong call in that this situation doesn't
happen ... well, it happened.

Looking at the `gitlab_branch_protection` resource I find that it's
kinda unclear what's going on, also looking at the upstream API docs
doesn't shed any lights on this as the documentation is quite sparse.
Some of this was lately raised by @beekeep in
https://github.com/gitlabhq/terraform-provider-gitlab/issues/878#issuecomment-1048902570
, that is that some fields are arguments in the provider, but optional
in the upstream API. Also the implemented logic to retrieve the set
`push_access_level` and `merge_access_level` can only be guessed when
trying to understand how those values come to be from a `POST` to a
`GET` request of the [Protected Branches
API](https://docs.gitlab.com/ee/api/protected_branches.html).

Closes #890

Author: timofurrer

CHANGELOG.md

@@ -1,3 +1,9 @@
+## 3.10.0 (2022-02-24)
+
+BUG FIXES:
+
+* resource/gitlab_branch_protection: Fix issue which claimed that `no valid access level` can be found ([#892](https://github.com/gitlabhq/terraform-provider-gitlab/pull/892))
+
 ## 3.10.0 (2022-02-23)
 
 FEATURES:
@@ -19,7 +25,7 @@ IMPROVEMENTS:
 * resource/gitlab_service_jira: Add `api_url` attribute ([#597](https://github.com/gitlabhq/terraform-provider-gitlab/pull/597))
 * resource/gitlab_user: Add `state` attribute to allow blocking users ([#762](https://github.com/gitlabhq/terraform-provider-gitlab/pull/762))
 
-BUG FIXES
+BUG FIXES:
 
 * datasource/gitlab_projects: Allow to get archived and unarchived repositories ([#855](https://github.com/gitlabhq/terraform-provider-gitlab/pull/855))
 * resource/gitlab_group: Support setting `default_branch_protection` to `0` ([#856](https://github.com/gitlabhq/terraform-provider-gitlab/pull/856))

internal/provider/resource_gitlab_branch_protection.go

@@ -173,16 +173,12 @@ func resourceGitlabBranchProtectionRead(ctx context.Context, d *schema.ResourceD
 		if err := d.Set("push_access_level", accessLevelValueToName[*pushAccessLevel]); err != nil {
 			return diag.Errorf("error setting push_access_level: %v", err)
 		}
-	} else {
-		return diag.Errorf("unable to get push_access_level: %v", err)
 	}
 
 	if mergeAccessLevels, err := firstValidAccessLevel(pb.MergeAccessLevels); err == nil {
 		if err := d.Set("merge_access_level", accessLevelValueToName[*mergeAccessLevels]); err != nil {
 			return diag.Errorf("error setting merge_access_level: %v", err)
 		}
-	} else {
-		return diag.Errorf("unable to get merge_access_level: %v", err)
 	}
 
 	if err := d.Set("allow_force_push", pb.AllowForcePush); err != nil {