allow patches with prefix a/ and b/ (try using -p1 if -p0 fails)

[prof7bit]

When using git it will become commonplace to have patches formatted with git diff or git format-patch and these prepend by default prefixes like a/ and b/ in front of the paths. A patch created by git diff and usable by git apply or by patch -p1 starts with a header like this:

diff --git a/ide/projectinspector.pas b/ide/projectinspector.pas
index 26ba1a2244..4ee5b58a49 100644
--- a/ide/projectinspector.pas
+++ b/ide/projectinspector.pas

while a patch acceptable by patch -p0 (current only possibility in fpcupdeluxe) would need to start like this:

diff --git a/ide/projectinspector.pas b/ide/projectinspector.pas
index 26ba1a2244..4ee5b58a49 100644
--- ide/projectinspector.pas
+++ ide/projectinspector.pas

As it turns out now I have to edit all patch files I receive from devs while trying to test their changes by hand to remove the prefixes or tell them to generate then with git diff --no-prefix which is very uncommon and nobody does this.

I would change the patching logic such that if it fails to apply the patch with -p0 also try again to apply it with -p1. Or maybe even the other way around and try -p1 first because most patches will now come straight out of git and will be of the -p1 type.

Also you should add the -t option for batch processing, so it outputs an error instead of trying to read user input from stdin.

[LongDirtyAnimAlf]

Please test:
https://github.com/LongDirtyAnimAlf/fpcupdeluxe/releases/tag/2.0.1e

[prof7bit]

Is working, tested with both types of patches :-)

closing this bug