Allow overwriting existing output file

[romanz]

Otherwise, rage fails with:

$ echo | rage -r age100qf7fggvctqclsqvl2xu6vjnrerxm9vt8x56yql6gaz9x54vcaqdh2q26 -o existing-file.age
Error: File exists (os error 17)

[codecov]

Codecov Report

Merging #168 (3e282b4) into main (9c56470) will increase coverage by 1.31%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main     #168      +/-   ##
==========================================
+ Coverage   34.90%   36.21%   +1.31%     
==========================================
  Files          33       33              
  Lines        2716     2764      +48     
==========================================
+ Hits          948     1001      +53     
+ Misses       1768     1763       -5     

Impacted Files	Coverage Δ
age/src/cli_common/file_io.rs	14.58% <100.00%> (+14.58%)	⬆️
age/src/protocol/decryptor.rs	45.16% <0.00%> (-1.72%)	⬇️
age-core/src/format.rs	75.00% <0.00%> (-1.67%)	⬇️
age/src/primitives/armor.rs	41.79% <0.00%> (-0.88%)	⬇️
age-core/src/plugin.rs	32.67% <0.00%> (-0.66%)	⬇️
age/src/i18n.rs	0.00% <0.00%> (ø)
age/src/scrypt.rs	48.97% <0.00%> (ø)
age/src/identity.rs	53.96% <0.00%> (+0.84%)	⬆️
age/src/format.rs	56.09% <0.00%> (+1.21%)	⬆️
age/src/ssh.rs	32.50% <0.00%> (+1.25%)	⬆️
... and 4 more

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[romanz]

IIUC, all the tests pass except uploading benchmarks - which fails with:

Must provide CRITERION_TOKEN in environment: export CRITERION_TOKEN="token"
Error: Process completed with exit code 1.

https://github.com/str4d/rage/pull/168/checks?check_run_id=1708942847

[romanz]

Ping :)

[str4d]

Thanks for the PR! I've been reluctant to merge it because I'm not personally a fan of just overwriting files, but after talking with @FiloSottile and some other sysadmins, I now agree that the more consistent UX is for -o to behave the same way as pipes, i.e. do what Unix does and overwrite the output.

[romanz]

Thanks!