Fix httpx is not encoding with symbol '%s' (#3140)

[Tunglies]

Fix httpx is not encoding with symbol '%s' (#3140)
Add url parsing test

Summary

Checklist

• I understand that this PR may be closed in case there was no previous discussion. (This doesn't apply to typos!)
• I've added a test for each change that was introduced, and I tried as much as possible to make a single atomic change.
• I've updated the documentation accordingly.

[T-256]

Suggested change

	i=0
	whilei<len(string):
	char=string[i]
	ifcharinNON_ESCAPED_CHARS:
	i+=1
	continue
	# Check if the character is a start of a valid percent-encoded sequence
	elif (
	char=="%"
	andi+2<len(string)
	andstring[i+1 : i+3].isalnum()
	andlen(string[i+1 : i+3]) ==2
	):
	i+=3
	else:
	returnFalse
	returnTrue
	# All characters must already be non-escaping or valid percent-encoded
	forindex, charinenumerate(string):
	ifcharnotinNON_ESCAPED_CHARSandnotPERCENT_ENCODED_REGEX.match(
	string[index : index+3]
	):
	returnFalse
	returnTrue

[Tunglies]

Thanks for review! I have applied the suggestion.

[T-256]

Thanks, I think it deserves a note in changelog.

[heysarthak]

Hi @T-256,
will the code change encode every "%" sent into uri as "%25" ?

[T-256]

Hi @T-256, will the code change encode every "%" sent into uri as "%25" ?

Yes, if it is invalid percent-encoded.

[heysarthak]

when can we merge this changes? @tomchristie

[jhominal]

Hello, could you look at if this PR fixes the cases of bad % character encoding that are raised in #3135?

I think the change in this PR (to only encode % if it would result in invalid percent-encoding) is a distraction from the real issue.

[lovelydinosaur]

Thanks. I think this is superseeded by #3187.

[heysarthak]

I tried the same on http 0.27.0, still having the same issue.

[lovelydinosaur]

Thanks everyone.
Remaining issues here should now all fully be addressed in #3371 and #3373.

(Test from this PR is included in the current test suite)