why does install-bundle fail with "insufficient fees" on mainnet? how to fix?

[dckc]

Recently @WietzeSlagman reported that an agd tx swingset install-bundle command that worked fine locally and on emerynet failed on mainnet:

code: 13
codespace: sdk
data: ""
events: []
gas_used: "0"
gas_wanted: "48319440"
height: "0"
info: ""
logs: []
raw_log: 'insufficient fees; got:  required: 1207986ubld: insufficient fee'

[dckc]

>0 Gas Prices on mainnet

In addition to the storage cost associated with installing bundles, ordinary cosmos sdk transaction fees still apply.

The gas prices on local networks and emerynet are 0, so no fees are required. But on mainnet, fees were instituted to mitigate spam.

So the solution was to supply at least 1207986ubld ... around 1.25BLD should suffice: --fees=1250000ubld.