Gsutil

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New Features
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- Add cp support for end-to-end encryption via the split-trust encryption tool (STET). (1338)

Bug Fixes
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- Use custom endpoints for resumable updloads on the XML API. (1333)

Other Changes
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- Dropped support for Python 2 to patch RSA security issues. (1339)
- Several documentation updates and clarifications.

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Bug Fixes
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- Improve content type inference for some common extensions. (1321)
- Copy Content-Encoding from first object in compose command. (1320)
- Support generation querying for ls command. (1319)

Other Changes
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- Add a message encouraging py3 upgrade. (1322)
- Update mock library version. (1315)
- Several documentation updates and clarifications.

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Bug Fixes
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- Update pyu2f to latest version to fix a security key reauth bug (1310)

Other Changes
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- Several documentation updates and clarifications.

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New Features
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- Onboard mTLS support with AIP-4114 for gsutil (1302)

Other Changes
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- Several documentation updates and clarifications.

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New Features
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- Add gsutil support for Public Access Prevention (1255)

Bug Fixes
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- Fix raising-bad-type yapf errors. (1303)

Other Changes
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- Link fix pointing to CGC docs again (1291).
- Backfill some small doc changes (1294)
- Small text tweak (1293)
- Update CHECKSUM and VERSION for 4.64 release.
- Update CHANGES.md for 4.64 release.
- Delete encryption addhelp page (1297)
- Putting cl/381035251 into github (1296)
- Backfill cl/381932961 (1298)

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Bug Fixes
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- None

Other Changes
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- Link fix pointing to CGC docs.