formulary: remove consts on cache clear

[Bo98]

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Fixes this -W1 warning:

/usr/local/Homebrew/Library/Homebrew/formulary.rb:47: warning: already initialized constant Formulary::FormulaNamespace05bf70582f35fd2a829a4b3b42cd7164
/usr/local/Homebrew/Library/Homebrew/formulary.rb:47: warning: previous definition of FormulaNamespace05bf70582f35fd2a829a4b3b42cd7164 was here

Steps to reproduce:

Formula["hello"]
Formulary.clear_cache
Formula["hello"]

[BrewTestBot]

Review period will end on 2021-02-18 at 15:15:52 UTC.

[MikeMcQuaid]

Nice catch!

[MikeMcQuaid]

Suggested change

	next unless namespace.deconstantize == name
	next if namespace.deconstantize != name

[MikeMcQuaid]

Suggested change

	cache.each do |k, m|
	cache.each do |klass, module|

assuming that's correct?

[Bo98]

k for key since it's either a pathname or a symbol - it's not consistent. But yes, I'll change these.

[MikeMcQuaid]

Ta!

[Bo98]

Also added a fix for another scenario when formula loading failed (it would not be stored in the cache but the const would remain).

[BrewTestBot]

Review period ended.

[MikeMcQuaid]

Great, thanks for this @Bo98!