tidy: convert Fprintf to Fprintln when possible

[rvantonder]

When the second argument to Fprintf contains no format specifiers (AKA "verbs"), use Fprint instead.

In our codebase, every pattern that matched the above also contains a \n at the end of the string, so we can further simplify the above and say that:

• if the string also ends with \n, use Fprintln instead.

Created with:

{
    "scopeQuery": "repo:github.com/sourcegraph/sourcegraph$",
    "matchTemplate":   "fmt.Fprintf(:[1], \":[2]\\n\")",
    "rewriteTemplate": "fmt.Fprintln(:[1], \":[2]\")"
}

[rvantonder]

Haha, oh, the test build failure is interesting:

That's a false positive in the linter, it's not redundant, because the original code does want to print two newlines.

[mrnugget]

How cool is that?!

[rvantonder]

@mrnugget apparently there's a thread on this: golang/go#18085 (comment) (creds @slimsag for hunting down the issue)

[codecov]

Codecov Report

Merging #7174 into master will not change coverage.
The diff coverage is 0%.

@@           Coverage Diff           @@
##           master    #7174   +/-   ##
=======================================
  Coverage   39.19%   39.19%           
=======================================
  Files        1230     1230           
  Lines       64159    64159           
  Branches     6066     6066           
=======================================
  Hits        25150    25150           
  Misses      36709    36709           
  Partials     2300     2300

Impacted Files	Coverage Δ
cmd/server/shared/postgres.go	0% <0%> (ø)	⬆️

[uwedeportivo]

i'm late to the party, but this is really cool