Align component version processing with omnibus

When we tag a release component version files are copied from GitLab
repository to Omnibus repository.

However the 2 process do not parse the file in the same way.

This commit ports omnibus logic into gitlab task_helpers

Related to https://gitlab.com/gitlab-com/gl-infra/delivery/issues/516

Fixes https://gitlab.com/gitlab-org/gitlab/issues/34873

doc/development/gitaly.md

@@ -166,12 +166,11 @@ end
 
 Normally, GitLab CE/EE tests use a local clone of Gitaly in
 `tmp/tests/gitaly` pinned at the version specified in
-`GITALY_SERVER_VERSION`. The `GITALY_SERVER_VERSION` file supports
-`=my-branch` syntax to use a custom branch in <https://gitlab.com/gitlab-org/gitaly>. If
+`GITALY_SERVER_VERSION`. The `GITALY_SERVER_VERSION` file supports also
+branches and SHA to use a custom commit in <https://gitlab.com/gitlab-org/gitaly>. If
 you want to run tests locally against a modified version of Gitaly you
 can replace `tmp/tests/gitaly` with a symlink. This is much faster
-because the `=my-branch` syntax forces a Gitaly re-install each time
-you run `rspec`.
+because if will avoid a Gitaly re-install each time you run `rspec`.
 
 ```shell
 rm -rf tmp/tests/gitaly

lib/gitlab/task_helpers.rb

@@ -158,15 +158,17 @@ module Gitlab
     end
 
     def checkout_or_clone_version(version:, repo:, target_dir:)
-      version =
-        if version.starts_with?("=")
-          version.sub(/\A=/, '') # tag or branch
-        else
-          "v#{version}" # tag
+      clone_repo(repo, target_dir) unless Dir.exist?(target_dir)
+      checkout_version(get_version(version), target_dir)
     end
 
-      clone_repo(repo, target_dir) unless Dir.exist?(target_dir)
-      checkout_version(version, target_dir)
+    # this function implements the same logic we have in omnibus for dealing with components version
+    def get_version(component_version)
+      # If not a valid version string following SemVer it is probably a branch name or a SHA
+      # commit of one of our own component so it doesn't need `v` prepended
+      return component_version unless /^\d+\.\d+\.\d+(-rc\d+)?$/.match?(component_version)
+
+      "v#{component_version}"
     end
 
     def clone_repo(repo, target_dir)

spec/tasks/gitlab/task_helpers_spec.rb

@@ -20,22 +20,12 @@ describe Gitlab::TaskHelpers do
     end
 
     it 'checkout the version and reset to it' do
+      expect(subject).to receive(:get_version).with(version).and_call_original
       expect(subject).to receive(:checkout_version).with(tag, clone_path)
 
       subject.checkout_or_clone_version(version: version, repo: repo, target_dir: clone_path)
     end
 
-    context 'with a branch version' do
-      let(:version) { '=branch_name' }
-      let(:branch) { 'branch_name' }
-
-      it 'checkout the version and reset to it with a branch name' do
-        expect(subject).to receive(:checkout_version).with(branch, clone_path)
-
-        subject.checkout_or_clone_version(version: version, repo: repo, target_dir: clone_path)
-      end
-    end
-
     context "target_dir doesn't exist" do
       it 'clones the repo' do
         expect(subject).to receive(:clone_repo).with(repo, clone_path)
@@ -96,4 +86,19 @@ describe Gitlab::TaskHelpers do
       expect { subject.run_command!(['bash', '-c', 'exit 1']) }.to raise_error Gitlab::TaskFailedError
     end
   end
+
+  describe '#get_version' do
+    using RSpec::Parameterized::TableSyntax
+
+    where(:version, :result) do
+      '1.1.1'                                    | 'v1.1.1'
+      'master'                                   | 'master'
+      '12.4.0-rc7'                               | 'v12.4.0-rc7'
+      '594c3ea3e0e5540e5915bd1c49713a0381459dd6' | '594c3ea3e0e5540e5915bd1c49713a0381459dd6'
+    end
+
+    with_them do
+      it { expect(subject.get_version(version)).to eq(result) }
+    end
+  end
 end