[FS#810] Sysupgrade fails since r4188-e96a9a9af8in (ipq806x R7800 NAND device)

[LEDE Bugs]

The following task has a new comment added:

FS#810 - Sysupgrade fails since r4188-e96a9a9af8in  (ipq806x R7800 NAND device) 
User who did this - build000 (build000)

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I confirm that sysupgrade works on NAND machines above version r4213:
1) clean install * img version r4214 by tftp (recovery system built into NETGEAR routers)
2) last firmware update from r4214 to r4215 // WNDR43 (7) 00 // successful - the traditional installation method (just for me by LuCI).
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More information can be found at the following URL:
https://bugs.lede-project.org/index.php?do=details&task_id=810#comment2684