Remove github.com/pkg/errors and replace with std library version

This is possible now that we no longer support go1.12 and brings
rclone into line with standard practices in the Go world.

This also removes errors.New and errors.Errorf from lib/errors and
prefers the stdlib errors package over lib/errors.

backend/b2/b2.go

@@ -9,6 +9,7 @@ import (
 	"bytes"
 	"context"
 	"crypto/sha1"
+	"errors"
 	"fmt"
 	gohash "hash"
 	"io"
@@ -19,7 +20,6 @@ import (
 	"sync"
 	"time"
 
-	"github.com/pkg/errors"
 	"github.com/rclone/rclone/backend/b2/api"
 	"github.com/rclone/rclone/fs"
 	"github.com/rclone/rclone/fs/accounting"
@@ -366,7 +366,7 @@ func errorHandler(resp *http.Response) error {
 
 func checkUploadChunkSize(cs fs.SizeSuffix) error {
 	if cs < minChunkSize {
-		return errors.Errorf("%s is less than %s", cs, minChunkSize)
+		return fmt.Errorf("%s is less than %s", cs, minChunkSize)
 	}
 	return nil
 }
@@ -381,7 +381,7 @@ func (f *Fs) setUploadChunkSize(cs fs.SizeSuffix) (old fs.SizeSuffix, err error)
 
 func checkUploadCutoff(opt *Options, cs fs.SizeSuffix) error {
 	if cs < opt.ChunkSize {
-		return errors.Errorf("%v is less than chunk size %v", cs, opt.ChunkSize)
+		return fmt.Errorf("%v is less than chunk size %v", cs, opt.ChunkSize)
 	}
 	return nil
 }
@@ -414,11 +414,11 @@ func NewFs(ctx context.Context, name, root string, m configmap.Mapper) (fs.Fs, e
 	}
 	err = checkUploadCutoff(opt, opt.UploadCutoff)
 	if err != nil {
-		return nil, errors.Wrap(err, "b2: upload cutoff")
+		return nil, fmt.Errorf("b2: upload cutoff: %w", err)
 	}
 	err = checkUploadChunkSize(opt.ChunkSize)
 	if err != nil {
-		return nil, errors.Wrap(err, "b2: chunk size")
+		return nil, fmt.Errorf("b2: chunk size: %w", err)
 	}
 	if opt.Account == "" {
 		return nil, errors.New("account not found")
@@ -463,7 +463,7 @@ func NewFs(ctx context.Context, name, root string, m configmap.Mapper) (fs.Fs, e
 	}
 	err = f.authorizeAccount(ctx)
 	if err != nil {
-		return nil, errors.Wrap(err, "failed to authorize account")
+		return nil, fmt.Errorf("failed to authorize account: %w", err)
 	}
 	// If this is a key limited to a single bucket, it must exist already
 	if f.rootBucket != "" && f.info.Allowed.BucketID != "" {
@@ -472,7 +472,7 @@ func NewFs(ctx context.Context, name, root string, m configmap.Mapper) (fs.Fs, e
 			return nil, errors.New("bucket that application key is restricted to no longer exists")
 		}
 		if allowedBucket != f.rootBucket {
-			return nil, errors.Errorf("you must use bucket %q with this application key", allowedBucket)
+			return nil, fmt.Errorf("you must use bucket %q with this application key", allowedBucket)
 		}
 		f.cache.MarkOK(f.rootBucket)
 		f.setBucketID(f.rootBucket, f.info.Allowed.BucketID)
@@ -512,7 +512,7 @@ func (f *Fs) authorizeAccount(ctx context.Context) error {
 		return f.shouldRetryNoReauth(ctx, resp, err)
 	})
 	if err != nil {
-		return errors.Wrap(err, "failed to authenticate")
+		return fmt.Errorf("failed to authenticate: %w", err)
 	}
 	f.srv.SetRoot(f.info.APIURL+"/b2api/v1").SetHeader("Authorization", f.info.AuthorizationToken)
 	return nil
@@ -558,7 +558,7 @@ func (f *Fs) getUploadURL(ctx context.Context, bucket string) (upload *api.GetUp
 		return f.shouldRetry(ctx, resp, err)
 	})
 	if err != nil {
-		return nil, errors.Wrap(err, "failed to get upload URL")
+		return nil, fmt.Errorf("failed to get upload URL: %w", err)
 	}
 	return upload, nil
 }
@@ -1048,7 +1048,7 @@ func (f *Fs) makeBucket(ctx context.Context, bucket string) error {
 					}
 				}
 			}
-			return errors.Wrap(err, "failed to create bucket")
+			return fmt.Errorf("failed to create bucket: %w", err)
 		}
 		f.setBucketID(bucket, response.ID)
 		f.setBucketType(bucket, response.Type)
@@ -1083,7 +1083,7 @@ func (f *Fs) Rmdir(ctx context.Context, dir string) error {
 			return f.shouldRetry(ctx, resp, err)
 		})
 		if err != nil {
-			return errors.Wrap(err, "failed to delete bucket")
+			return fmt.Errorf("failed to delete bucket: %w", err)
 		}
 		f.clearBucketID(bucket)
 		f.clearBucketType(bucket)
@@ -1124,7 +1124,7 @@ func (f *Fs) hide(ctx context.Context, bucket, bucketPath string) error {
 				return nil
 			}
 		}
-		return errors.Wrapf(err, "failed to hide %q", bucketPath)
+		return fmt.Errorf("failed to hide %q: %w", bucketPath, err)
 	}
 	return nil
 }
@@ -1145,7 +1145,7 @@ func (f *Fs) deleteByID(ctx context.Context, ID, Name string) error {
 		return f.shouldRetry(ctx, resp, err)
 	})
 	if err != nil {
-		return errors.Wrapf(err, "failed to delete %q", Name)
+		return fmt.Errorf("failed to delete %q: %w", Name, err)
 	}
 	return nil
 }
@@ -1364,7 +1364,7 @@ func (f *Fs) getDownloadAuthorization(ctx context.Context, bucket, remote string
 		return f.shouldRetry(ctx, resp, err)
 	})
 	if err != nil {
-		return "", errors.Wrap(err, "failed to get download authorization")
+		return "", fmt.Errorf("failed to get download authorization: %w", err)
 	}
 	return response.AuthorizationToken, nil
 }
@@ -1669,14 +1669,14 @@ func (file *openFile) Close() (err error) {
 
 	// Check to see we read the correct number of bytes
 	if file.o.Size() != file.bytes {
-		return errors.Errorf("object corrupted on transfer - length mismatch (want %d got %d)", file.o.Size(), file.bytes)
+		return fmt.Errorf("object corrupted on transfer - length mismatch (want %d got %d)", file.o.Size(), file.bytes)
 	}
 
 	// Check the SHA1
 	receivedSHA1 := file.o.sha1
 	calculatedSHA1 := fmt.Sprintf("%x", file.hash.Sum(nil))
 	if receivedSHA1 != "" && receivedSHA1 != calculatedSHA1 {
-		return errors.Errorf("object corrupted on transfer - SHA1 mismatch (want %q got %q)", receivedSHA1, calculatedSHA1)
+		return fmt.Errorf("object corrupted on transfer - SHA1 mismatch (want %q got %q)", receivedSHA1, calculatedSHA1)
 	}
 
 	return nil
@@ -1716,7 +1716,7 @@ func (o *Object) getOrHead(ctx context.Context, method string, options []fs.Open
 		if resp != nil && (resp.StatusCode == http.StatusNotFound || resp.StatusCode == http.StatusBadRequest) {
 			return nil, nil, fs.ErrorObjectNotFound
 		}
-		return nil, nil, errors.Wrapf(err, "failed to %s for download", method)
+		return nil, nil, fmt.Errorf("failed to %s for download: %w", method, err)
 	}
 
 	// NB resp may be Open here - don't return err != nil without closing