fix: handle apt showpkg warnings

Author: Copilot

src/cmd/apt_query/testlogs/testnormalizedlist_virtualpackagesexists_stdoutsconcretepackage.log

@@ -11,9 +11,9 @@ EXECUTION-OBJ-END
 2025/03/15 22:29:14 EXECUTION-OBJ-START
 {
  "Cmd": "apt-cache showpkg libvips",
- "Stdout": "libvips42 8.9.1-2 (= )\n",
+ "Stdout": "Package: libvips\nReverse Provides:\nlibvips42 8.9.1-2 (= )\n",
  "Stderr": "",
- "CombinedOut": "libvips42 8.9.1-2 (= )\n",
+ "CombinedOut": "Package: libvips\nReverse Provides:\nlibvips42 8.9.1-2 (= )\n",
  "ExitCode": 0
 }
 EXECUTION-OBJ-END

src/internal/common/apt.go

@@ -53,6 +53,9 @@ func getNonVirtualPackage(executor exec.Executor, name string) (pkg *AptPackage,
 		if !inReverseProvides || strings.HasPrefix(trimmed, "W: ") || isErrLine(trimmed) {
 			continue
 		}
+		if strings.HasSuffix(trimmed, ":") {
+			break
+		}
 		splitLine := GetSplitLine(trimmed, " ", 3)
 		if len(splitLine.Words) < 2 {
 			continue

src/internal/common/apt_test.go

@@ -8,11 +8,11 @@ import (
 	execpkg "awalsh128.com/cache-apt-pkgs-action/src/internal/exec"
 )
 
-type stubExecutor struct {
+type mockExecutor struct {
 	executions map[string]*execpkg.Execution
 }
 
-func (s stubExecutor) Exec(name string, arg ...string) *execpkg.Execution {
+func (s mockExecutor) Exec(name string, arg ...string) *execpkg.Execution {
 	cmd := name + " " + strings.Join(arg, " ")
 	execution, ok := s.executions[cmd]
 	if !ok {
@@ -21,8 +21,8 @@ func (s stubExecutor) Exec(name string, arg ...string) *execpkg.Execution {
 	return execution
 }
 
-func TestGetNonVirtualPackage_IgnoresWarningsAfterReverseProvides(t *testing.T) {
-	executor := stubExecutor{
+func TestGetNonVirtualPackage_WithWarningsInReverseProvides(t *testing.T) {
+	executor := mockExecutor{
 		executions: map[string]*execpkg.Execution{
 			"apt-cache showpkg libopenblas0-openmp": {
 				Cmd: "apt-cache showpkg libopenblas0-openmp",