fix: fix downloader bug, missing cache update

[zong-zhe]

1. Does this PR affect any open issues?(Y/N) and add issue references (e.g. "fix #123", "re #123".):

• N
• Y

re #478

2. What is the scope of this PR (e.g. component or file name):

3. Provide a description of the PR(e.g. more details, effects, motivations or doc link):

• Affects user behaviors
• Contains syntax changes
• Contains variable changes
• Contains experimental features
• Performance regression: Consumes more CPU
• Performance regression: Consumes more Memory
• Other

4. Are there any breaking changes?(Y/N) and describe the breaking changes(e.g. more details, motivations or doc link):

• N
• Y

5. Are there test cases for these changes?(Y/N) select and add more details, references or doc links:

• Unit test
• Integration test
• Benchmark (add benchmark stats below)
• Manual test (add detailed scripts or steps below)
• Other

[coveralls]

Pull Request Test Coverage Report for Build 11066647634

Details

• 0 of 29 (0.0%) changed or added relevant lines in 2 files are covered.
• 1 unchanged line in 1 file lost coverage.
• Overall coverage decreased (-0.04%) to 41.278%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
pkg/downloader/downloader.go	0	9	0.0%
pkg/utils/utils.go	0	20	0.0%

Files with Coverage Reduction	New Missed Lines	%
pkg/downloader/downloader.go	1	36.21%

Totals
Change from base Build 11048517978:	-0.04%
Covered Lines:	3469
Relevant Lines:	8404

---

💛 - Coveralls

[Peefy]

LGTM

[He1pa]

lgtm