Otherwise, we percent-encode negative signed chars incorrectly. For
example, https://www.strava.com/login contains the following hidden
<input> field:
<input name="utf8" type="hidden" value="✓" />
On submitting the form, we would percent-encode that field as:
utf8=%-1E%-64%-6D
Which would cause us to receive an HTTP 500 response. We now properly
percent-encode that field as:
utf8=%E2%9C%93
And can login to Strava :^)