allow ignoring releases by regular expression

6.7.0 was a weird release since there was a lot of new behaviour added
to master between 6.6.0 and 6.7.0, but 6.7.0 received very few of
those changes. However, we have merged 6.7.x back into master, so the
tags are clearly present on master.  In this unusual case, we want to
ignore the 6.7.x release, since otherwise the PRs merged pre-6.7.0 won't
be included.

This commit adds the flag `--ignore-release-regex` which takes a regular
expression of release names to ignore.

e.g.
```
--ignore-release-regex '^v6\.7\.\d+'
```

matches all 6.7.x releases

Signed-off-by: Aidan Oldershaw <[email protected]>

cmd/generate.go

@@ -3,6 +3,7 @@ package cmd
 import (
 	"fmt"
 	"os"
+	"regexp"
 
 	"github.com/clarafu/release-me/generate"
 	"github.com/clarafu/release-me/github"
@@ -22,6 +23,7 @@ func init() {
 	generateCmd.Flags().String("github-branch", "master", "the branch name of the github repository to pull the pull requests from")
 	generateCmd.Flags().String("last-commit-SHA", "", "will generate a release note using all prs merged up to this commit SHA. If empty, will generate release note until latest commit.")
 	generateCmd.Flags().String("release-version", "", "the version that the release note will be generated for")
+	generateCmd.Flags().String("ignore-release-regex", "", "a regular expression indicating releases to ignore when determining the previous release")
 	generateCmd.MarkFlagRequired("release-version")
 }
 
@@ -33,13 +35,29 @@ func generateReleaseNote(cmd *cobra.Command, args []string) {
 	githubOwner, _ := cmd.Flags().GetString("github-owner")
 	githubRepo, _ := cmd.Flags().GetString("github-repo")
 
+	ignoreReleaseRegexStr, _ := cmd.Flags().GetString("ignore-release-regex")
+
 	// Fetch previous 50 releases from the repository and grab the commit hash
 	// associated to each release
 	releaseSHAs, err := client.FetchCommitsFromReleases(githubOwner, githubRepo)
 	if err != nil {
 		failf("failed to fetch release commit SHAs from github: %s", err)
 	}
 
+	if ignoreReleaseRegexStr != "" {
+		filteredReleaseSHAs := make(map[string]string)
+		ignoreReleaseRegex, err := regexp.Compile(ignoreReleaseRegexStr)
+		if err != nil {
+			failf("invalid regex in --ignore-release-regex: %s", err)
+		}
+		for oid, release := range releaseSHAs {
+			if !ignoreReleaseRegex.MatchString(release) {
+				filteredReleaseSHAs[oid] = release
+			}
+		}
+		releaseSHAs = filteredReleaseSHAs
+	}
+
 	githubBranch, _ := cmd.Flags().GetString("github-branch")
 
 	// Starting from the latest commit on the branch, we want to walk backwards