cmd/gerritbot/internal/rules: stop complaining about trailing period after bug number

Some contributors (including on the core Go team) prefer to end
the bug number reference with a trailing period, like 'For #nnn.',
so adjust the GitHub PR rules to allow that without complaint.

The Contribution Guide does not use that style in its examples,
but https://go.dev/wiki/CommitMessage was updated to mention
it is allowed.

Updates golang/go#61573

Change-Id: Idac4cef24bff22241dfc786684fe536def12f24f
Reviewed-on: https://go-review.googlesource.com/c/build/+/525975
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
Reviewed-by: Heschi Kreinick <heschi@google.com>
Auto-Submit: Dmitri Shuralyov <dmitshur@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>

Author: thepudds

cmd/gerritbot/internal/rules/rules.go

@@ -322,22 +322,22 @@ var ruleGroups = [][]rule{
 			name: "body: bug format looks incorrect",
 			skip: []string{"proposal"},
 			f: func(change Change) (finding string, note string) {
-				finding = "Do you have the right bug reference format? %s (without a period) at the end of the commit message."
+				finding = "Do you have the right bug reference format? %s at the end of the commit message."
 				if mightBeTrivial(change) {
 					return "", ""
 				}
 				var bugPattern string
 				switch {
 				case change.Repo == "go":
-					bugPattern = `#\d{4,}$`
+					bugPattern = `#\d{4,}`
 				case usesTracker(change.Repo) == mainTracker:
-					bugPattern = `golang/go#\d{4,}$`
+					bugPattern = `golang/go#\d{4,}`
 				case usesTracker(change.Repo) == ownTracker:
-					bugPattern = fmt.Sprintf(`golang/%s#\d{2,}$`, change.Repo)
+					bugPattern = fmt.Sprintf(`golang/%s#\d{2,}`, change.Repo)
 				default:
-					bugPattern = `golang/go#\d{4,}$`
+					bugPattern = `golang/go#\d{4,}`
 				}
-				if !match(`(?m)^(Fixes|Updates|For|Closes|Resolves) `+bugPattern, change.Body) {
+				if !match(`(?m)^(Fixes|Updates|For|Closes|Resolves) `+bugPattern+`\.?$`, change.Body) {
 					return fmt.Sprintf(finding, bugExamples(change.Repo)), commitMessageAdvice
 				}
 				return "", ""

cmd/gerritbot/internal/rules/rules_test.go

@@ -41,7 +41,7 @@ To edit the commit message, see instructions [here](https://github.com/golang/go
 			want: `Possible problems detected:
   1. The commit title should start with the primary affected component name followed by a colon, like "src/goInstallTools: improve [...]".
   2. The first word in the commit title after the component should be a lowercase English word (usually a verb).
-  3. Do you have the right bug reference format? For the vscode-go repo, the format is usually 'Fixes golang/vscode-go#1234' or 'Updates golang/vscode-go#1234' (without a period) at the end of the commit message.
+  3. Do you have the right bug reference format? For the vscode-go repo, the format is usually 'Fixes golang/vscode-go#1234' or 'Updates golang/vscode-go#1234' at the end of the commit message.
 
 To edit the commit message, see instructions [here](https://github.com/golang/go/wiki/GerritBot/#how-does-gerritbot-determine-the-final-commit-message). For guidelines on commit messages for the Go project, see [here](https://go.dev/doc/contribute#commit_messages).
 `,