Reftest: add pin command test #3620

Job	Run time
Analyse	4s
Build-Linux (4.08.1)	2m 15s
Cygwin	4s
Build-macOS (4.14.1)	2m 6s
Build-Linux (4.09.1)	1m 57s
Hygiene	17s
Build-Linux (4.10.2)	2m 9s
Test-macOS (4.14.1)	25m 37s
Build-Linux (4.11.2)	2m 19s
Build-Linux (4.12.1)	1m 53s
Build-Linux (4.13.1)	2m 1s
Build-Linux (5.0.0)	2m 3s
Build-Linux (5.1.1)	2m 14s
Build-Linux (4.14.1)	1m 49s
Build-Windows (x86_64-pc-cygwin, x86_64-pc-cygwin, 4.14.1)	27m 40s
Build-Windows (i686-w64-mingw32, x86_64-pc-cygwin, 4.14.1)	36m 31s
Build-Windows (x86_64-w64-mingw32, x86_64-pc-cygwin, 4.14.1)	35m 3s
Build-Windows (i686-pc-windows, x86_64-pc-cygwin, 4.14.1)	39m 47s
Build-Windows (x86_64-pc-windows, x86_64-pc-cygwin, 4.14.1)	42m 30s
Cold-Linux	4m 35s
Test-Linux (4.14.1)	13m 5s
Upgrade-Linux (4.14.1)	1m 5s
Solvers-Linux (z3, 4.14.1)	50s
Solvers-Linux (0install, 4.14.1)	1m 17s
Upgrade-macOS (4.14.1)	1m 51s
Solvers-macOS (z3, 4.14.1)	1m 10s
Solvers-macOS (0install, 4.14.1)	1m 15s
	4h 13m 27s

Provide feedback