Fix shellcheck warnings in pull-all/merge-all scripts

[nmathewson]

This appears at first glance to be a shellcheck bug.

Closes 29747. Bugfix not in any released Tor.

[coveralls]

Pull Request Test Coverage Report for Build 4171

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 1196 unchanged lines in 36 files lost coverage.
• Overall coverage decreased (-1.6%) to 61.719%

---

Files with Coverage Reduction	New Missed Lines	%
src/feature/hs/hs_service.c	1	73.85%
src/feature/dirclient/dirclient.c	1	18.37%
src/feature/nodelist/nodelist.c	2	71.88%
src/core/or/policies.c	2	84.52%
src/feature/nodelist/microdesc.c	2	72.75%
src/lib/buf/buffers.c	2	90.93%
src/feature/client/addressmap.c	2	60.54%
src/feature/rend/rendcache.c	2	93.02%
src/lib/evloop/token_bucket.h	2	66.67%
src/lib/fs/files.c	2	67.21%

Totals
Change from base Build 4154:	-1.6%
Covered Lines:	45346
Relevant Lines:	73472

---

💛 - Coveralls