That was the intention all along.

Replace the variable `magit--display-core-upgrade-instructions',
making it easier to use this for more than one dependency.

That library requires `magit-section', which performs the extended
version of this kludge.

It appears that for some users `static-if' expands to nothing if
the THEN or ELSE part is a `defalias' form (whichever is used in
their case).  I got similar reports when using `static-if' like
this in other packages, but I was never able to reproduce these
issues.

Workaround this by placing the `static-if' inside the `defalias'.
Another workaround, which appears to work, would be to wrap both
THEN and ELSE with `progn'.

Closes #5557.

`dabbrev-capf' does not call `user-error'; in actuality it merely
includes in its return value a function, which calls `user-error'.
That function is what needs to be advised to neuter that incorrect
use of `user-error'.

Also use `condition-case' instead of `cl-letf'.

Closes #5559.

Suggested-by: Stefan Monnier <monnier@iro.umontreal.ca>

Only augment the predicate if there actually is one.

Fix problem introduced in d527f833.

The new `magit--meta-hunk-p' is a kludge, instead we should
define proper types for these "not-quite-a-hunk" sections.

Closes #5554.