The == form is non-portable and not supported everywhere. Here is the explanation for this issue from pkgsrc:
The "test" command, as well as the "[" command, are not required to know
the "==" operator. Only a few implementations like bash and some
versions of ksh support it.
When you run "test foo == foo" on a platform that does not support the
"==" operator, the result will be "false" instead of "true". This can
lead to unexpected behavior.
There are two ways to fix this error message. If the file that contains
the "test ==" is needed for building the package, you should create a
patch for it, replacing the "==" operator with "=". If the file is not
needed, add its name to the CHECK_PORTABILITY_SKIP variable in the
package Makefile.
sneves
commented
5 years ago
The == form is non-portable and not supported everywhere. Here is the explanation for this issue from pkgsrc:
The "test" command, as well as the "[" command, are not required to know
the "==" operator. Only a few implementations like bash and some versions of ksh support it.
When you run "test foo == foo" on a platform that does not support the
"==" operator, the result will be "false" instead of "true". This can
lead to unexpected behavior.
There are two ways to fix this error message. If the file that contains
the "test ==" is needed for building the package, you should create a
patch for it, replacing the "==" operator with "=". If the file is not
needed, add its name to the CHECK_PORTABILITY_SKIP variable in the
package Makefile.