fix(submodules): auto handle "commits not present" patch creation error

When "commits not present" error occurs during patch creation between FROM and TO commits,
then reset service git worktree to the FROM commit (which in turn fetches lost submodule commit)
and retry patch creation procedure.

Signed-off-by: Timofey Kirillov <timofey.kirillov@flant.com>

pkg/git_repo/base.go

@@ -225,7 +225,31 @@ func (repo *Base) createPatch(ctx context.Context, repoPath, gitDir, repoID, wor
 
 	var desc *true_git.PatchDescriptor
 	if hasSubmodules {
+		var retryCount int
+
+	TryCreatePatch:
 		desc, err = true_git.PatchWithSubmodules(ctx, fileHandler, gitDir, workTreeCacheDir, true_git.PatchOptions(opts))
+
+		if true_git.IsCommitsNotPresentError(err) && retryCount == 0 {
+			logboek.Context(ctx).Default().LogF("Detected not present commits when creating patch: %s\n", err)
+			logboek.Context(ctx).Default().LogF("Will switch worktree to original commit %q and retry\n", opts.FromCommit)
+
+			if err := fileHandler.Truncate(0); err != nil {
+				return nil, fmt.Errorf("unable to truncate file %s: %w", tmpFile, err)
+			}
+			if _, err := fileHandler.Seek(0, 0); err != nil {
+				return nil, fmt.Errorf("unable to reset file %s: %w", tmpFile, err)
+			}
+
+			if err := true_git.WithWorkTree(ctx, gitDir, workTreeCacheDir, opts.FromCommit, true_git.WithWorkTreeOptions{HasSubmodules: true}, func(workTreeDir string) error {
+				return nil
+			}); err != nil {
+				return nil, fmt.Errorf("unable to switch worktree to commit %q: %w", opts.FromCommit, err)
+			}
+
+			retryCount++
+			goto TryCreatePatch
+		}
 	} else {
 		desc, err = true_git.Patch(ctx, fileHandler, gitDir, true_git.PatchOptions(opts))
 	}

pkg/true_git/diff_parser.go

@@ -2,6 +2,7 @@ package true_git
 
 import (
 	"bytes"
+	"errors"
 	"fmt"
 	"io"
 	"os"
@@ -13,6 +14,12 @@ import (
 	"github.com/werf/werf/pkg/util"
 )
 
+var ErrCommitsNotPresent = errors.New("commits not present")
+
+func IsCommitsNotPresentError(err error) bool {
+	return err != nil && strings.HasSuffix(err.Error(), ErrCommitsNotPresent.Error())
+}
+
 func makeDiffParser(out io.Writer, pathScope string, pathMatcher path_matcher.PathMatcher, fileRenames map[string]string) *diffParser {
 	return &diffParser{
 		PathScope:   pathScope,
@@ -379,7 +386,7 @@ func (p *diffParser) handleModifyFilePathB(line string) error {
 func (p *diffParser) handleSubmoduleLine(line string) error {
 	p.state = unrecognized
 	if strings.HasSuffix(line, " (commits not present)") {
-		return fmt.Errorf("cannot handle \"commits not present\" in git diff line %q, check specified submodule commits are correct", line)
+		return fmt.Errorf("cannot handle git diff line %q, check specified commits are correct: %w", line, ErrCommitsNotPresent)
 	}
 	return nil
 }