Fall back to default application credentials when all other credentials sources fail
This change allows users with default application credentials
configured (notably when running on google compute instances) to
dispense with explicitly configuring google cloud storage credentials
in rclone's own configuration.
This enables MD5 checksum calculation and publication when uploading file above the "Cutoff" limit.
It was explictely ignored in case of multi-block (a.k.a. multipart) uploads to Azure Blob Storage.
Make the pacer package more flexible by extracting the pace calculation
functions into a separate interface. This also allows to move features
that require the fs package like logging and custom errors into the fs
package.
Also add a RetryAfterError sentinel error that can be used to signal a
desired retry time to the Calculator.
Bitrix Site Manager emits `<D:resourcetype><collection/></D:resourcetype>`
missing the namespace on the `collection` tag. This causes the item
to be identified as a file instead of a directory.
To work around this look at the Microsoft extension prop
`iscollection` which seems to be emitted as well.
Before this change any attempt to access a google doc in an rclone
mount would give the error "partial downloads are not supported while
exporting Google Documents" as the mount uses ranged requests to read
data.
This implements ranged requests for a limited number of scenarios,
just enough so that Google docs can be cat-ed from an rclone mount.
When they are cat-ed then they receive their correct size also.
Before this change the union remote was using whether the writable
union could poll for changes to decide whether the union mount could
poll for changes.
The fix causes the union backend to signal it can poll for changes if
**any** of the remotes can poll for changes.
Before this change it was setting the modification times of the things
that the symlinks pointed to.
Note that this is only implemented for unix style OSes. Other OSes
will not attempt to set the modification time of a symlink.
If the upload concurrency is set > 1 then the hash becomes corrupted.
The upload is fine, and can be downloaded fine, however the hash is no
longer the md5sum of the object. It is not known whether this is
rclone's fault or a bug at QingStor.
