Restore graceful restart on SIGHUP

[zeripath]

There was a mistaken change in #10001 which broke graceful restart on SIGHUP.

This PR restores this.

[codecov-io]

Codecov Report

Merging #10224 into master will decrease coverage by <.01%.
The diff coverage is 54.79%.

@@            Coverage Diff             @@
##           master   #10224      +/-   ##
==========================================
- Coverage   43.64%   43.64%   -0.01%     
==========================================
  Files         576      576              
  Lines       79716    79787      +71     
==========================================
+ Hits        34791    34820      +29     
- Misses      40627    40664      +37     
- Partials     4298     4303       +5

Impacted Files	Coverage Δ
models/pull.go	41.36% <0%> (-0.47%)	⬇️
modules/graceful/manager_unix.go	40.83% <0%> (ø)	⬆️
routers/repo/issue.go	37.61% <10%> (-0.4%)	⬇️
routers/user/home.go	56.2% <80%> (+0.87%)	⬆️
models/issue_list.go	68.2% <88%> (+1.27%)	⬆️
services/pull/temp_repo.go	29.05% <0%> (-2.57%)	⬇️
services/pull/patch.go	60.37% <0%> (-2.52%)	⬇️
services/pull/check.go	32.92% <0%> (-2.44%)	⬇️

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[jolheiser]

Looks better than before. 👀

[lunny]

make L-G-T-M work