Terraform vault provider: set VAULT_CLIENT_TIMEOUT

The default value of 60 seconds for VAULT_CLIENT_TIMEOUT in the terraform vault provider will fail on some requests resulting in a “context deadline exceeded” error and an abort of the apply. Documentation says that some VAULT_* environment variables are used by the vault provider. However setting VAULT_CLIENT_TIMEOUT makes no difference - the default 60s timeout still is used. Is there a way to change the timeout setting?