This is a test if a URL is recognized by "gf", with the cursor before and
after the "://".  Also test ":\\".  Tricky: Have to use backslashes in a file
name!

STARTTEST
:.,$w!/tmp/vimtest2a
/first
/tmp
gf
:.,$w!/tmp/vimtest2b
/second
/URL
gf
:set isf=@,48-57,/,.,-,_,+,,,$,:,~,\
:.,$w!\\tmp\\vimtest2c
/third
/name
gf
:.,$w!\\tmp\\vimtest2d
/fourth
G/URL
gf
:!rm /tmp/vimtest2a /tmp/vimtest2b \\tmp\\vimtest2c \\tmp\\vimtest2d
:wq! test.out
ENDTEST
This is the text for the vimtest2a file.
This is the text for the vimtest2b file.
This is the text for the vimtest2c file.
This is the text for the vimtest2d file.
This is a first test for an URL://machine.name/tmp/vimtest2a and some other text
This is a second test for an URL://machine.name/tmp/vimtest2b and some other text
This is a third test for an URL:\\machine.name\tmp\vimtest2c and some other text
This is a fourth test for an URL:\\machine.name\tmp\vimtest2d and some other text