shellrc: fixed nnn plugin install/update #185

Job	Run time
linux/fedora:41/admin / bootstrap	3m 43s
linux/fedora:40/admin / bootstrap	1h 31m 39s
linux/fedora:41/dev_single / bootstrap	3m 50s
linux/fedora:40/dev_single / bootstrap	1h 32m 19s
linux/archlinux:latest/admin / bootstrap	1h 54m 7s
macos/macos-14/admin / bootstrap	14m 32s
linux/archlinux:latest/dev_single / bootstrap	1h 53m 29s
macos/macos-14/dev_single / bootstrap	39s
macos/macos-13/admin / bootstrap	23m 28s
macos/macos-13/dev_single / bootstrap	1m 21s
	7h 39m 7s

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