Harden curl output parsing #2886

Job	Run time
Analyse	5s
Build-macOS (4.14.1)	2m 21s
Hygiene	26s
Cygwin	15s
Build-Linux (4.08.1)	2m 18s
Test-macOS (4.14.1)	17m 37s
Build-Linux (4.09.1)	2m 17s
Build-Linux (4.10.2)	2m 20s
Build-Linux (4.11.2)	2m 14s
Build-Linux (4.12.1)	2m 11s
Build-Linux (4.13.1)	2m 16s
Build-Linux (5.0.0)	2m 12s
Build-Linux (5.1.1)	2m 45s
Build-Linux (4.14.1)	2m 5s
Build-Windows (x86_64-pc-cygwin, x86_64-pc-cygwin, 4.14.1)	38m 27s
Build-Windows (i686-w64-mingw32, x86_64-pc-cygwin, 4.14.1)	48m 36s
Build-Windows (x86_64-w64-mingw32, x86_64-pc-cygwin, 4.14.1)	47m 35s
Build-Windows (i686-pc-windows, x86_64-pc-cygwin, 4.14.1)	52m 6s
Build-Windows (x86_64-pc-windows, x86_64-pc-cygwin, 4.14.1)	51m 7s
Upgrade-macOS (4.14.1)	1m 36s
Solvers-macOS (z3, 4.14.1)	1m 11s
Solvers-macOS (0install, 4.14.1)	1m 10s
Cold-Linux	5m 44s
Test-Linux (4.14.1)	10m 58s
Upgrade-Linux (4.14.1)	1m 14s
Solvers-Linux (z3, 4.14.1)	1m 12s
Solvers-Linux (0install, 4.14.1)	1m 18s
	5h 3m 36s

Provide feedback