cmd/update-bash.sh: print message on fetch fail.
cmd/update-bash.sh: print message on fetch fail.

Closes Homebrew/homebrew#49107.
Closes Homebrew/homebrew#49105.
Closes Homebrew/homebrew#48267.

Signed-off-by: Mike McQuaid <a17fed27eaa842282862ff7c1b9c8395a26ac320@mikemcquaid.com>

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