Fixed URI sometimes not Deleted

[midorinet]

I've implemented #36 however even tough I've fixed uri such as /images/image.jpg, cache doesn't removed

On debug log, sometimes I saw http file cache purge with partial enabled running even I loop the same URI without wildcard

Onother weird debug log that I found key is not deleted is like below

2021/06/03 08:30:58 [debug] 9#9: http cache file "/data/nginx/1a33c4ca21ce8/9/3f/0d8c2799f208c5e0781d98945e6043f9" key read: "1a33c4ca21ce8/assets/web_1.0/fonts/roboto-v18-latin-300.woff2-https://andy.handsome.local2òØœŽ–´¤kp�*��Ô/•üÌ¢�f�"£°÷�[��îx�z�´�·ÙïÖ´úK�ç¬�xJ
UÎÀv�±¨ñ��6�žþܳ�Ë�>#ì×h¬
˜w�Vâšõˆ
]»ÊŸ³¸êµø®�¹È­$�˜_=u�é*Ñá�d_‹7ÁjUeTQñ3_yRŸ�W�*“�cýÚ§ã)Ó©‹3 ©Ð|ÿ"

[denji]

I see this code is unstable, I'll move it to the unstable development branch.