librustzcash fails to sync account with birthday set to sapling activation height

[AArnott]

After I create an account with a birthday height set to exactly the sapling activation height (419200) or +1 (419201), sync fails with the following error:

status: Unknown, message: "zcashd did not return treestate", details: [], metadata: MetadataMap { headers: {"content-type": "application/grpc"} }

The viewing key I used in the test was as follows, but I don't think that's relevant:

zxviews1q0duytgcqqqqpqre26wkl45gvwwwd706xw608hucmvfalr759ejwf7qshjf5r9aa7323zulvz6plhttp5mltqcgs9t039cx2d09mgq05ts63n8u35hyv6h9nc9ctqqtue2u7cer2mqegunuulq2luhq3ywjcz35yyljewa4mgkgjzyfwh6fr6jd0dzd44ghk0nxdv2hnv4j5nxfwv24rwdmgllhe0p8568sgqt9ckt02v2kxf5ahtql6s0ltjpkckw8gtymxtxuu9gcr0swvz.

librustzcash version: 5a2a670ffca5d8