processes metedata continuous spaces

[QSummerY]

As suggested with issue boto/botocore#2409
Upload may fail when there is a continuous space

[stevearc]

The linked issue is talking about leading/trailing whitespace, not multiple space characters in a row. This seems like a value.strip() would be more appropriate?

[QSummerY]

SignatureDoesNotMatch occurs when I try to upload. After local verification, the signature parsing will be affected if continuous Spaces appear. Non-ascii characters in metadata are removed from the normalize_metadata_value method, after removing the continuous space may come up.
This linked issue is similar to mine, and I also tried the situation with Spaces at the beginning and the end, but the upload is normal, only the continuous space will be affected

[stevearc]

Out of curiosity, which object storage provider is giving you this signature error?

[stevearc]

This will replace all whitespace characters with " ". Could we instead do

re.sub(r"  +", " ", value)

to only replace instances of two-or-more spaces with a single space?

[QSummerY]

I tried the presence of other whitespace characters, the same problem would occur if \t existed, and the presence of \n and \r would succeed, but the characters after the whitespace were removed.
And observing that only X-AMZ-meta-summary affects the request, the values processed include the following.

 'x-amz-meta-hash-sha256': '71eccb33ac8b2584c86f36f8ebfbe72c0a98022b576f411ab05773343e4e2cac', 
 'x-amz-meta-hash-md5': 'f562366338d015df143c7afacabdee44', 
 'x-amz-meta-summary': ' Python3\tweb , WSGI, Web ', 
 'x-amz-meta-name': 'frontgate', 
 'x-amz-meta-version': '0.6.39'

So I think it's going to be implemented the same way as before.

[QSummerY]

It's the COS of Tencent Cloud.

[stevearc]

Okay, last request:
This is going to replace all kinds of whitespace with spaces. It would be better if we could preserve the original whitespace if it's not causing issues. I believe this should do it

re.sub(r'(\s)\s+', r'\1', value)

[QSummerY]

Because I have tried to only exist /t will also appear, and if you keep the original, it will cause the same problem. So I think it should look like this

return re.sub(r"\s+", " ", value)

[stevearc]

Wow COS really doesn't like whitespace, huh? I guess this is fine. The worst that we expect is some mangling of the summary formatting.

[coveralls]

Coverage remained the same at 82.916% when pulling 5930658 on QSummerY:processes_continuous_spaces into 477ca21 on stevearc:master.

[stevearc]

One last request before merging