$ {
  echo -e "-----BEGIN PGP PRIVATE KEY BLOCK-----"
  cat __tests__/fixtures/test-key-committer.pgp
  echo -e "\n-----END PGP PRIVATE KEY BLOCK-----\n"
} | gpg --import --batch --yes -
gpg: invalid armor header: lQdGBGGX3iEBEACqKHI35iK8y5lODg00/Uck4PDxxACldsT6OR01dmrDV2U0JYXw\n
gpg: key 27304EDD6079B81C: "A committer <committer@example.com>" not changed
gpg: key 27304EDD6079B81C: secret key imported
gpg: Total number processed: 1
gpg:              unchanged: 1
gpg:       secret keys read: 1
gpg:  secret keys unchanged: 1

That code return error code 2 and this extra line:

gpg: invalid armor header: lQdGBGGX3iEBEACqKHI35iK8y5lODg00/Uck4PDxxACldsT6OR01dmrDV2U0JYXw\n

Fixed by adding a '\n' at the end of the header:

$ {
  echo -e "-----BEGIN PGP PRIVATE KEY BLOCK-----\n"
  cat __tests__/fixtures/test-key-committer.pgp
  echo -e "\n-----END PGP PRIVATE KEY BLOCK-----\n"
} | gpg --import --batch --yes -
gpg: key 27304EDD6079B81C: "A committer <committer@example.com>" not changed
gpg: key 27304EDD6079B81C: secret key imported
gpg: Total number processed: 1
gpg:              unchanged: 1
gpg:       secret keys read: 1
gpg:  secret keys unchanged: 1