t5505: fix pwd on Windows again
The earlier commit
b74e70b3 set $PWD to the particular 'pwd' form to use
on Windows and *nix platforms. But this is not good for two reasons: $PWD
has a predefined meaning to the shell (it influences pwd itself), and
all occurrences of 'pwd' must be replaced by $PWD. This new fix now simply
replaces 'pwd' by a shell function on Windows only, where we can be
reasonably certain that 'bash' is in use, so that the function can call
the builtin 'pwd' explicitly.
Signed-off-by: Johannes Sixt <johannes.sixt@telecom.at>