Harden curl output parsing #2972

Job	Run time
Analyse	7s
Test-macOS (4.14.1)	29m 15s
Build-Linux (4.08.1)	2m 20s
Build-macOS (4.14.1)	5m 16s
Cygwin	3s
Build-Linux (4.09.1)	2m 12s
Hygiene	41s
Build-Linux (4.10.2)	2m 11s
Build-Linux (4.11.2)	2m 4s
Build-Linux (4.12.1)	2m 7s
Build-Linux (4.13.1)	2m 17s
Build-Linux (5.0.0)	2m 5s
Build-Linux (5.1.1)	2m 3s
Build-Linux (4.14.1)	2m 47s
Build-Windows (x86_64-pc-cygwin, x86_64-pc-cygwin, 4.14.1)	48m 39s
Build-Windows (i686-w64-mingw32, x86_64-pc-cygwin, 4.14.1)	49m 39s
Build-Windows (x86_64-w64-mingw32, x86_64-pc-cygwin, 4.14.1)	49m 13s
Build-Windows (i686-pc-windows, x86_64-pc-cygwin, 4.14.1)	52m 25s
Build-Windows (x86_64-pc-windows, x86_64-pc-cygwin, 4.14.1)	52m 37s
Upgrade-Linux (4.14.1)	1m 2s
Test-Linux (4.14.1)	15m 12s
Cold-Linux	5m 0s
Solvers-Linux (z3, 4.14.1)	1m 8s
Solvers-Linux (0install, 4.14.1)	1m 27s
Upgrade-macOS (4.14.1)	1m 36s
Solvers-macOS (z3, 4.14.1)	1m 16s
Solvers-macOS (0install, 4.14.1)	1m 28s
	5h 36m 10s

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