Description of problem:
rpmsign --delsign fails to remove Signature on certain 3rd party RPMs

Version-Release number of selected component (if applicable):
rpm-sign-4.14.2-37.el8.x86_64

How reproducible:
With proper RPM very

Steps to Reproduce:
1. Download RPM with known issue, like IBM's GPFS or MSFT teams.  Teams is publicly available at:
   https://www.microsoft.com/en-us/microsoft-365/microsoft-teams/download-app#desktopAppDownloadregion

2. Attempt to remove signature

3. Observe return-code, possible error message, or verify signature was removed


Actual RHEL 7 results:

  $ rpmsign --delsign teams-1.3.00.16851-1.x86_64.rpm 
  teams-1.3.00.16851-1.x86_64.rpm:

  $ echo $?
  255


Actual RHEL 8 results:

  $ rpm -qp --info gpfs.msg.en_US-5.0.5-1.noarch.rpm 2>/dev/null | grep ^Signature
  Signature   : RSA/SHA256, Thu 09 Jul 2020 02:25:57 PM CDT, Key ID bdbe75c3efeb6eeb

  $ rpmsign --delsign gpfs.msg.en_US-5.0.5-1.noarch.rpm 
  gpfs.msg.en_US-5.0.5-1.noarch.rpm:
  error: gpfs.msg.en_US-5.0.5-1.noarch.rpm: rpmReadSignature failed: signature region 62: tag number mismatch il 12 ril 7 dl 1279 rdl 16

  $ rpm -qp --info gpfs.msg.en_US-5.0.5-1.noarch.rpm 2>/dev/null | grep ^Signature
  Signature   : RSA/SHA256, Thu 09 Jul 2020 02:25:57 PM CDT, Key ID bdbe75c3efeb6eeb



Expected results, using a previous version of the 3rd party GPFS RPM:

  $ rpm -qp --info ./gpfs.msg.en_US-5.0.3-0.noarch.rpm 2>/dev/null | grep ^Signature
  Signature   : RSA/SHA1, Tue 30 Apr 2019 04:44:05 PM CDT, Key ID 89cc8c5a5c9e89bc

  $ rpmsign --delsign gpfs.msg.en_US-5.0.3-0.noarch.rpm 
  gpfs.msg.en_US-5.0.3-0.noarch.rpm:

  $ rpm -qp --info ./gpfs.msg.en_US-5.0.3-0.noarch.rpm 2>/dev/null | grep ^Signature
  Signature   : (none)


Additional info: