Add squash-merge support into oc adm release info

Repositories, like insights-operator, use squash-merge and
`oc adm release info --changes-from` does not show changes for these repos.

This PR adds handling also squash merging and shows changes.

pkg/cli/admin/release/git.go

@@ -163,8 +163,9 @@ func gitOutputToError(err error, out string) error {
 }
 
 var (
-	rePR     = regexp.MustCompile(`^Merge pull request #(\d+) from`)
-	rePrefix = regexp.MustCompile(`^(\[[\w\.\-]+\]\s*)+`)
+	squashRePR = regexp.MustCompile(`#(\d+)`)
+	rePR       = regexp.MustCompile(`^Merge pull request #(\d+) from`)
+	rePrefix   = regexp.MustCompile(`^(\[[\w\.\-]+\]\s*)+`)
 )
 
 func mergeLogForRepo(g gitInterface, repo string, from, to string) ([]MergeCommit, error) {
@@ -194,6 +195,20 @@ func mergeLogForRepo(g gitInterface, repo string, from, to string) ([]MergeCommi
 		}
 	}
 
+	squash := false
+	if out == "" {
+		// some repositories use squash merging(like insights-operator) and
+		// out which is populated by --merges flag is empty. Thereby,
+		// we are trying to get git log with --no-merges flag for that repositories
+		// in order to get the logs.
+		args = []string{"log", "--no-merges", "--topo-order", "-z", "--pretty=format:%H %P%x1E%ct%x1E%s%x1E%b", fmt.Sprintf("%s..%s", from, to)}
+		out, err = g.exec(args...)
+		if err != nil {
+			return nil, gitOutputToError(err, out)
+		}
+		squash = true
+	}
+
 	if klog.V(5).Enabled() {
 		klog.Infof("Got commit info:\n%s", strconv.Quote(out))
 	}
@@ -220,20 +235,30 @@ func mergeLogForRepo(g gitInterface, repo string, from, to string) ([]MergeCommi
 		}
 
 		msg := records[3]
+		if squash {
+			msg = records[2]
+		}
+
 		mergeCommit.Bugs, msg = extractBugs(msg)
 		msg = strings.TrimSpace(msg)
 		msg = strings.SplitN(msg, "\n", 2)[0]
 
 		mergeMsg := records[2]
-		if m := rePR.FindStringSubmatch(mergeMsg); m != nil {
-			mergeCommit.PullRequest, err = strconv.Atoi(m[1])
-			if err != nil {
-				return nil, fmt.Errorf("could not extract PR number from %q: %v", mergeMsg, err)
-			}
+		var m []string
+		if !squash {
+			m = rePR.FindStringSubmatch(mergeMsg)
 		} else {
+			m = squashRePR.FindStringSubmatch(mergeMsg)
+		}
+
+		if m == nil || len(m) < 2 {
 			klog.V(2).Infof("Omitted commit %s which has no pull-request", mergeCommit.Commit)
 			continue
 		}
+		mergeCommit.PullRequest, err = strconv.Atoi(m[1])
+		if err != nil {
+			return nil, fmt.Errorf("could not extract PR number from %q: %v", mergeMsg, err)
+		}
 		if len(msg) == 0 {
 			msg = "Merge"
 		}

pkg/cli/admin/release/git_test.go

@@ -9,10 +9,14 @@ import (
 )
 
 type fakeGit struct {
-	input string
+	input  string
+	squash bool
 }
 
 func (g fakeGit) exec(commands ...string) (string, error) {
+	if commands[1] == "--merges" && g.squash {
+		return "", nil
+	}
 	return g.input, nil
 }
 
@@ -23,6 +27,7 @@ func Test_mergeLogForRepo(t *testing.T) {
 		repo    string
 		from    string
 		to      string
+		squash  bool
 		want    []MergeCommit
 		wantErr bool
 	}{
@@ -205,10 +210,46 @@ func Test_mergeLogForRepo(t *testing.T) {
 				},
 			},
 		},
+		{
+			input:  "abc\x1e1\x1eBugs 1743564: fix typo (#145)\x1e * fix typo",
+			squash: true,
+			want: []MergeCommit{
+				{
+					ParentCommits: []string{}, Commit: "abc", PullRequest: 145, CommitDate: time.Unix(1, 0).UTC(),
+					Bugs: BugList{
+						Bugs: []Bug{
+							{
+								ID:     1743564,
+								Source: Bugzilla,
+							},
+						},
+					},
+					Subject: "fix typo (#145)",
+				},
+			},
+		},
+		{
+			input:  "abc\x1e1\x1eOCPBUGS-1743564: fix typo (#145)\x1e * fix typo",
+			squash: true,
+			want: []MergeCommit{
+				{
+					ParentCommits: []string{}, Commit: "abc", PullRequest: 145, CommitDate: time.Unix(1, 0).UTC(),
+					Bugs: BugList{
+						Bugs: []Bug{
+							{
+								ID:     1743564,
+								Source: Jira,
+							},
+						},
+					},
+					Subject: "fix typo (#145)",
+				},
+			},
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			g := fakeGit{input: tt.input}
+			g := fakeGit{input: tt.input, squash: tt.squash}
 			got, err := mergeLogForRepo(g, tt.repo, "a", "b")
 			if (err != nil) != tt.wantErr {
 				t.Errorf("mergeLogForRepo() error = %v, wantErr %v", err, tt.wantErr)