gnutls fail for cert-tests.pkcs7 when build with libtans1-4.6.

[宋文武]

when update libtasn1 from 4.5 to 4.6, gnutls fail to pass the
cert-tests.pkcs7 test, get:
  import error: ASN1 parser: Error in DER parsing.

with libtasn1-4.5, the test does pass.
is this an known issue?