Using prev/next cursors continually adds too many random numbers to querystring

[vcarl]

The CallBuilder class always adds a random string to get around the cache, and it doesn't get removed by the backend when it builds the next/prev/self links. This means every time the prev/next functions are called, the URL gets longer. After polling for new trades for a while, I ended up with

https://horizon.stellar.org/trades
?base_asset_type=native
&c=0.7701431022730245
&c=0.4970337975240551
&c=0.07568927670193881
&c=0.7113043831916186
&c=0.09741669585793411
&c=0.9634440653137242
&c=0.7952843831838561
&c=0.4240534929325275
&c=0.9077095637476096
&c=0.4545434659180798
&c=0.6947631341816114
&c=0.49686492877708144
&c=0.7644129797904986
&c=0.9781990404740941
&c=0.6122502549735962
&c=0.2561399182905837
&c=0.14784270381840492
&counter_asset_code=HKDT
&counter_asset_issuer=GABSZVZBYEO5F4V5LZKV7GR4SAJ5IKJGGOF43BIN42FNDUG7QPH6IMRQ
&counter_asset_type=credit_alphanum4
&cursor=77931417081745409-0
&limit=10
&order=asc

Looks like changing this line to replace instead of add would fix the issue. https://github.com/stellar/js-stellar-sdk/blob/master/src/call_builder.js#L165

[nullstyle]

The proposed solution, making sure the c value is replaced instead of appended onto the query string, seems like the correct solution to me.